Organic species that facilitate charge transfer to or from nanostructures

ABSTRACT

The present invention provides compositions (small molecules, oligomers and polymers) that can be used to modify charge transport across a nanocrystal surface or within a nanocrystal-containing matrix, as well as methods for making and using the novel compositions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 10/656,910, filed Sep.4, 2003, which is related to U.S. provisional applications U.S. Ser. No.60/408,722, filed Sep. 5, 2002; and U.S. Ser. No. 60/452,232, filed Mar.4, 2003. The present application claims priority to and benefit of eachof these prior applications, which are hereby incorporated herein byreference in their entirety for all purposes.

FIELD OF THE INVENTION

The present invention is in the field of nanotechnology. Moreparticularly, the present invention is directed to conductive ligandsand matrices for use with nanostructures, as well as related methods forproducing and using the conductive compositions, and related devicesincorporating the conductive compositions.

BACKGROUND OF THE INVENTION

Polymer-based light-emitting and photovoltaic devices, including thoseincorporating nanocrystal-containing polymers are known in the art. Theperformance of polymer-based photovoltaic devices has been improved,e.g., by embedding semiconductor nanocrystals into the polymer matrix.For example, nanocomposite-based photovoltaic devices are described inWO 04/022637 and WO 04/023527. However, the performance of these andother devices that employ nanocrystals can be further improved.

Semiconducting nanocrystals can be designed with specific opticalproperties and/or electronic structures, in part by controlling the sizeand shape of the nanocrystals used as part of the light harvestingelement in the photovoltaic devices. In addition, the polymeric matrixencompassing the nanocrystal can be selected to also absorb light.However, charge transport within the photovoltaic device is generallylimited by matrix constraints, rather than by the absorption propertiesof the nanocrystals. As a result, charge transport through the matrixand/or among the nanocrystals is an important element of optimalphotovoltaic operation.

Nanocrystal syntheses typically produce particles having surfaces coatedwith a surfactant layer, e.g., a layer of molecules having longaliphatic chains, such as alkyl phosphonic acids, alkyl amines, alkylcarboxylic acids, alkyl phosphines or alkyl phosphine oxides. Theseligands form a substantially non-conductive layer on the nanocrystalsurface. In applications in which it is desirable to efficiently removeor add charges to nanocrystalline structures, the residual aliphaticligand layer limits the charge transfer to the surface. Synthesis ofwater soluble semiconductor nanocrystals capable of light emission aredescribed, for example, in U.S. Pat. No. 6,251,303 to Bawendi et al.entitled “Water-soluble fluorescent nanocrystals” (Jun. 6, 2001) andU.S. Pat. No. 6,319,426 to Bawendi et al. titled “Water-solublefluorescent semiconductor” (Nov. 20, 2001).

While conductive polymers are known in the art (see, for example, H. S.Nalwa (ed.), Handbook of Organic Conductive Molecules and Polymers, JohnWiley & Sons 1997; U.S. Pat. No. 6,399,224 to Li, “Conjugated Polymerswith Tunable Charge Injection Ability”; and U.S. Pat. No. 5,504,323 toHeeger et al., “Dual function conducting polymer diodes”), thesepolymers do not have any functional group(s) that can bind strongly to ananocrystal surface. As such, these polymers do not make optimal contactwith the nanocrystal.

The performance of nanocrystal-based light-emitting and photovoltaicdevices would be improved if the removal or addition of charges via thenanocrystals was more energetically efficient. Accordingly, there existsa need in the art for improved ligands for use with nanocrystalstructures. The present invention meets these and other needs byproviding novel compositions for use with nanocrystals, as well asmethods for making and using the novel compositions. A completeunderstanding of the invention will be obtained upon review of thefollowing.

SUMMARY OF THE INVENTION

The present invention provides compositions (small molecules, oligomersand polymers) that can be used to modify charge transport across asurface or a nanostructure (e.g., nanocrystal) surface, or within ananostructure (e.g., nanocrystal)-containing matrix, as well as methodsfor making and using the novel compositions. The compositions contain aconjugated organic species and at least one binding group capable ofinteracting with a nanostructure (e.g., nanocrystal) surface; duringuse, the compositions are coupled via the binding group to thenanostructure (e.g., nanocrystal) surface, such that the compositionsare substantially conductive to electrons and/or holes being transportedby/through the nanostructure (e.g., nanocrystal) (e.g., during theprocess of extracting or injecting the electrons or holes). Thecompositions of the present invention can optionally be derivatized withadditional chemical groups, e.g., to enhance the electronic conjugationof the core organic species, to couple adjacent nanostructures (e.g.,nanocrystals), or to facilitate dispersion, mixing and/or blending ofnanostructures (e.g., nanocrystals) in various matrices.

In one aspect, the present invention provides conductive compositionsfor modification of charge transport across a nanostructure (e.g.,nanocrystal)-containing matrix. The conductive composition typicallyinclude a) a conjugated organic moiety as the “body structure,” or coreof the conductive molecule; b) a nanostructure (e.g.,nanocrystal)-binding “head group” coupled to the body structure at afirst position on the conjugated organic moiety; and c) a “tail group”coupled to the body structure at a second position on the conjugatedorganic moiety. After formation of an exciton in the nanostructure(e.g., nanocrystal)-containing matrix, the conductive compositionfacilitates the injection and/or extraction of charge (electron and/orhole) with respect to the attached nanostructure, thereby modifyingcharge transport across a nanostructure-containing matrix.

The modular nature of the composition (and the corresponding methods forsynthesizing the composition) lends itself toward modification oradjustment of the various elements of the composition (head, body, tail)based upon the desired use. As such, various constituents can be usedfor the different composition elements. For example, the body structuretypically comprises a conjugated alkyl moiety or a conjugated arylmoiety (e.g., a phenylene, thiophene, ethene, ethyne, aniline, fluorene,pyridine, perylene, phenanthralene, anthracene, an alkynyl, or apolynuclear aromatic moiety). Chemical structures for use as thefunctionalized head group include, but are not limited to, one or morephosphonic acid, carboxylic acid, amine, phosphine, sulfonate,sulfinate, or thiol moieties. Tail group structures can be eitherconducting or nonconducting chemical moieties; preferred tail groupsubstituents include, but are not limited to, 1-propyne, 1-butyne,1-pentyne, 1-hexyne, 1-heptyne, 1-octyne, 1-nonyne, 1-decyne, or analkyne comprising between 3 and 22 carbons. Optionally, either or boththe head group and the tail group further include one or more thiophenemoieties positioned between the body structure and the head or tailsubstituent.

In some embodiments, the tail group also includes a nanostructure (e.g.,nanocrystal)-binding moiety (e.g., a phosphonic acid, carboxylic acid,amine, phosphine, or thiol moiety). Furthermore, thenanostructure-binding head group and/or nanostructure-binding tail groupcan provide either a single chemical moiety for attachment to thenanostructure (i.e., monodentate) or multiple binding moieties (i.e.,multidentate). Optionally, these moieties are chosen or selected fortheir ability to bind to selected types of nanostructures (for example,the head group(s) selectively bind p-type nanocrystals while the tailgroup(s) selectively bind n-type nanocrystals).

The body structure optionally includes one or more additionalsubstituents, or “sidechains,” coupled to the conjugated organicspecies. In some embodiments, the sidechains are O-linked or N-linkedsidechains coupled to the conjugated organic moiety. Addition of thesidechain (or other substituent) to the body structure preferably doesnot destroy the conjugation of the core organic species; rather, in someembodiments, the sidechain moiety or moieties extend the conjugation. Assuch, substituents for use as sidechain elements can include, but arenor limited to, an electron donating group, an electron withdrawinggroup, a conducting chemical structure, a nonconducting chemicalstructure, or various reactive functional groups or polymerizableelements (such as an acrylate moiety, a methacrylate moiety, or a vinylmoiety). In some embodiments, the sidechain is matched functionallyand/or electronically to the nanostructure (e.g.,nanocrystal)-containing matrix; in other embodiment, the sidechainelement simply alters the solubility of the composition. Preferably, theconjugated compositions of the present invention have two sidechainsubstituents coupled to the body structure; however, the chemicalcompositions of the side chains need not be identical. Optionally, thesidechains can be employed to link and/or align adjacent nanostructures.

Exemplary sidechain substituents for use in the compositions of thepresent invention include, but are not limited to, an O-linked hexanemoiety, an O-linked 2-ethylhexyl moiety, an O-linked octyl moiety, anO-linked decyl moiety, an N-linked hexane moiety, an N-linked2-ethylhexyl moiety, an N-linked octyl moiety, and an N-linked decylmoiety. However, any N-linked or O-linked alkyl moiety having between 1and 22 (or more) carbons are contemplated for use in the presentinvention.

In some embodiments of the present invention, the body structureemployed in the conductive composition is an oligomeric or polymericstructure, rather than a monomeric chemical structure. Exemplarymultimeric body structure components include, but are not limited to,poly(phenylene), poly(thiophene), poly(ethene), poly(ethyne),poly(aniline), poly(fluorene), poly(pyridine), poly(polynuclear)moieties, and combinations thereof. Optionally, the multimeric bodystructure is composed of two or more monomeric body structure elementslinked by a linker region, such as a dithiophene moiety. Preferably thelinker element allows or enhances electronic conjugation between thebody structure elements. As with the monomeric embodiments, themultimeric body structure can optionally include one or more sidechainscoupled to one or more elements of the oligomeric or polymericstructure.

The present invention also provides polymeric conductive compositionsfor use with nanostructure (e.g., nanocrystal) structures (e.g., in thecase of nanocrystals, either as a nanocrystal coating or as a polymermatrix). The polymeric conductive compositions have the structure[H_(x)-B_(y)-T_(z)]_(n), wherein H comprises at least one functionalizedhead group capable of binding to a nanostructure surface or at least onehead group bound to a nanostructure surface; wherein B comprises a bodystructure comprising one or more conjugated organic moieties, wherein afirst conjugated organic moiety is coupled to a proximal functionalizedhead group or bound head group; wherein T comprises at least one tailgroup coupled to the body structure; and wherein x, y, z and nindependently comprise integers equal to or greater than 1. The sum ofthe integers x, y, z and n is equal to or greater than 5, such that atleast one element (head, body or tail) is present in more than one“copy” in the polymeric conductive composition. The polymeric conductivecomposition is synthesized by polymerization of monomeric precursorsthrough coupling of various polymerizable elements on one or more of thesubstituents.

In these polymeric conductive compositions, the head group optionally isone or more phosphonic acid, carboxylic acid, amine, phosphine,phosphine oxide or thiol moieties; the body structure is optionally aphenylene, thiophene, ethene, ethyne, aniline, fluorene, pyridine,perylene, phenanthralene, anthracene, an alkenyl moiety, a polynucleararomatic moiety, or polymer thereof; and the tail group is optionally a1-propyne, 1-butyne, 1-pentyne, 1-hexyne, 1-heptyne, 1-octyne, 1-nonyne,1-decyne, or an alkyne comprising between 3 and 22 carbons. In furtherembodiments, the body structure further comprises one or more O-linkedor N-linked substituents (e.g., electron donating or electronwithdrawing groups, conducting chemical structures, or nonconductingchemical structures) coupled to one or more polymer subunits (e.g.,member conjugated organic moieties). These O-linked of N-linkedsubstituents can be used, e.g., to alter the electronic signature of thecomposition, or alter the solubility of the polymeric conductivecomposition.

As an additional aspect, the present invention provides nanostructure(e.g., nanocrystal)-containing matrix compositions. In one embodiment,the nanostructure-matrix composition includes a nanostructure coupled toa conductive composition (e.g., ligand) of the present invention, and amatrix positioned proximal to the ligand-conjugated exterior surface ofthe nanostructure. Optionally, the matrix is also covalently coupled tothe nanostructure-bound conductive composition. In a preferredembodiment, the conductive composition is functionally or electronicallymatched to one or more substituents of the matrix.

In another embodiment, the nanostructure (e.g., nanocrystal)-containingmatrix composition includes a nanostructure and a matrix composed of thepolymeric conductive composition of the present invention. In oneembodiment, a portion of the nanostructure exterior surface is coupledto the polymeric matrix. In another embodiment, the nanostructure isderivatized or functionalized with a conductive composition of thepresent invention prior to being embedded in the polymeric conductivecomposition. Optionally, the polymeric conductive composition and thenanostructure-bound conductive composition are matched functionallyand/or electronically. In addition, the matrix composition and theconductive composition can optionally be covalently coupled.

In a further embodiment of the present invention, thenanostructure-matrix composition includes a conductive composition ofthe present invention coupled at a first position to a firstnanostructure (e.g., nanocrystal) and coupled at a second position to asecond nanostructure, and a matrix positioned proximal to the exteriorsurfaces of the nanostructure. In one optional example, the firstnanostructure is a p-type nanocrystal, and the second nanostructure is an-type nanocrystal.

The present invention also provides methods of synthesizing an organiccomposition that facilitates charge transfer for use in ananostructure-containing device. The organic compositions made usingthese methods are particularly suitable for use in a photovoltaicdevice. The methods include the steps of: a) providing a conjugatedorganic precursor, wherein the conjugated organic precursor comprises atleast three positions available for attachment of substituent modules(e.g., head, tail and sidechain); b) providing a first substituentmodule, wherein the first substituent module comprises a phosphonic acidderivative, a carboxylic acid derivative, an amine derivative, aphosphine derivative, a thiol derivative, a thiophene derivative, or acombination thereof; c) providing a second substituent module, whereinthe second substituent module comprises an alkyne derivative comprisingbetween three and 22 carbons; d) optionally providing a thirdsubstituent module, wherein the optional third substituent modulecomprises an alkyl derivative comprising between one and 22 carbons; ande) coupling the first substituent module at a first position, couplingthe second substituent module at a second position, and optionallycoupling the third substituent module at a third position, therebysynthesizing the organic composition.

At least one substituent of the first, second or third substituentmodules is capable of binding to a nanostructure surface (or,optionally, the component is already bound to a nanostructure surface).Coupling of the various modules to the body structure does not destroythe electronic conjugation of the body structure. Rather, in a preferredembodiment, coupling of one or more of the substituent modules to thebody structure extends the conjugation of the body structure.

In some embodiments of the present invention, the first substituentmodule is a thiophene derivative. The thiophene-containing head groupsubstituent module can be prepared, for example, by a) providing anarylhalide core structure; b) lithiating the arylhalide core structureat a first halide position and reacting with chlorotrimethylsilane(TMSCl) to yield a TMS-aryl intermediate core structure; c) lithiatingthe intermediate core structure at a second halide position and reactingthe product with trimethyltinchloride (Me₃SnCl) to yield a stannylatedsecond intermediate; and d) combining the second intermediate with ahalogenated thiophene to form a first substituent module comprising aTMS-aryl-thiophene derivative. Coupling the phosphite moiety to theTMS-aryl-thiophene derivative can be achieved, for example, byperforming a palladium-catalyzed phosphite-aryl coupling. The firstsubstituent module can be functionalized with the nanostructure-bindingmoiety (e.g., the phosphite group) either prior to coupling of themodule to the body structure, or after the module has been attached.

Coupling of an alkyne moiety employed as the second substituent modulecan be performed, e.g., via a Sonogashira coupling. Optionally, the bodystructure has been functionalized with thiophene moieties at the first(e.g., head) and/or second (e.g., tail) positions prior to addition ofthe head and tail moieties.

Various reactions can be employed to couple the optional thirdsubstituent to the body structure. For example, alkylation reactions(e.g., a Williamson ether synthesis, a Friedel-Crafts alkylationreaction, or other aromatic electrophilic substitution reaction) can beused to couple the third substituent to the conjugated organic precursorat a third position having a hydroxyl or amine moiety, to form asidechain-substituted intermediate composition.

In a preferred embodiment, the optional third substituent module (e.g.,one or more sidechains) is coupled to the conjugated organic precursorprior to attachment of the first and/or second substituent modules. Forexample, providing and coupling the third substituent module caninclude: a) providing about 1.1 molar equivalents of a halogenatedderivative of a sidechain substituent; b) combining the halogenatedderivative with the conjugated organic precursor in the presence ofpotassium carbonate (K₂CO₃) and dimethyl formamide (DMF) to form areaction mixture; and c) heating the reaction mixture to about 70° C.,thereby coupling the third substituent to the conjugated organic moiety.

Optionally, additional sidechain substituents can be added to theconjugated organic precursor during the third substituent coupling step.For example, coupling the third substituent module optionally furtherincludes coupling a fourth substituent to the body structure at a fourthposition. The third and fourth substituents can be the same or differentchemical species.

In some embodiments of the present invention, the methods of making theconductive composition also include the step of coupling or cojoiningthe head group (and any other nanostructure-binding moietiesincorporated into the composition) to an external surface of ananostructure, thereby providing a nanostructure-bound composition.Optionally, this step an be performed during the synthesis of theconductive composition (e.g., solid phase synthesis).

For embodiments utilizing substituent modules having polymerizablecomponents incorporated therein, the methods of making the conductivecomposition can optionally further include the step of polymerizing theorganic composition after coupling the composition to the nanostructuresurface, thereby forming a polymerized conjugated organic composition.

As a further aspect, the present invention also provides methods ofmodifying an interaction between a nanostructure (such as a nanocrystal)and an external matrix. The methods include the steps of a) treating ananostructure with a conductive composition the present invention; andb) forming a nanostructure -containing matrix comprising the treatednanostructure and a matrix composition, thereby modifying theinteraction between the nanostructure and the external matrix.Optionally, the conductive composition applied to the nanostructure canbe polymerized in situ, to form a polymerized conductive composition. Inanother embodiment, the matrix composition into which the coatednanostructure is placed constitutes the polymeric conductive compositionof the present invention.

The present invention also provides devices, such as optoelectricdevices, photovoltaic devices and light-emitting devices (LEDs)incorporating the conductive compositions of the present invention. Theconductive compositions of the present invention can be coupled toeither nanoscale and non-nanoscale (e.g., bulk crystalline) assemblies.The devices of the present invention typically include a first electrodesurface and a second electrode surface, and having a semiconductor ornanostructure-containing matrix composition comprising the conductivecompositions disposed between the two electrodes and electricallycoupled to the first electrode surface and the second electrode surface.In one embodiment, the conductive compositions of the present inventionare incorporated into photovoltaic devices, such as those described inWO 04/022637 and WO 04/023527. Alternatively, the compositions of thepresent invention can be used for charge injection into a fluorescentcore/shell nanostructure containing device, e.g., to make an LED for useas a display or white light source.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides exemplary conductive compositions of the presentinvention.

FIG. 2 provides additional exemplary conductive compositions of thepresent invention.

FIG. 3 depicts a chemical synthesis scheme for one embodiment of thecompositions of the present invention.

FIG. 4 depicts a chemical synthesis scheme for another embodiment of thecompositions of the present invention.

FIG. 5 depicts a chemical synthesis scheme for a further embodiment ofthe compositions of the present invention.

FIG. 6 depicts a chemical synthesis scheme for an additional embodimentof the compositions of the present invention.

FIG. 7 depicts a chemical synthesis scheme for a further embodiment ofthe compositions of the present invention.

FIG. 8 provides a pictorial representation of a further embodiment ofthe present invention depicting both monomeric and polymeric conductivecompositions.

FIGS. 9 through 19 provide mass spectral and/or NMR data for exemplaryintermediates and compositions of the present invention.

FIGS. 20 through 28 depict additional chemical synthesis schemes foradditional embodiments of the present invention.

DETAILED DESCRIPTION

The present invention provides conductive small molecules, oligomers andpolymers that can be used to modify charge transport across ananostructure surface or within a nanostructure-containing matrix (e.g.,a nanocomposite, e.g., comprising one or more nanocrystals, e.g., one ormore inorganic nanocrystals).

Photovoltaic devices convert light (solar energy) into storable energy.When light is absorbed by nanocrystalline structures in a nanocomposite(e.g., a nanocrystal-containing composition), the absorption results inthe formation of an electron-hole pair (also termed an “exciton”). Theelectron and hole can either recombine or remain separated, depending inpart upon the configuration of the nanocomposite. Recombination ofelectrons and holes is desirable in some applications (e.g., lightemission in LEDs) and undesirable in other applications.

In nanocomposites employed in photovoltaic devices, for example, theelectron and hole preferably do not recombine, but rather travel toopposite electrodes. However, nanostructures (e.g., nanowires, branchednanowires, nanocrystals, amorphous nanostructures, nanoparticles,nanotetrapods, etc.) typically comprise one or more surface ligands(such as surfactant molecules introduced during synthesis) that arenonconductive in nature. See e.g. U.S. patent application 60/389,029(filed Jun. 13, 2002) by Empedocles entitled “Nanotechnology enabledoptoelectronics” and Milliron et al. (2003) “Electroactive surfactantdesigned to mediate electron transfer between CdSe nanocrystals andorganic semiconductors” Adv. Mater. 15:58-61. The presence of thesenonconductive nanostructure coatings reduces the efficiency of chargeseparation in the photovoltaic device. The compositions of the presentinvention are designed to moderate, enhance, or otherwise control thetransport (e.g., separation) of the electron and hole generated in thenanocomposite. During use, the compositions are coupled to thenanocrystal surface, such that a conjugated organic species in thecomposition interacts electronically with the electrons and/or holesbeing transmitted through the nanocrystal. As noted above, this is incontrast with the currently-available organic nanocrystalline coatings,which are nonconductive in nature.

DEFINITIONS

Before describing the present invention in detail, it is to beunderstood that this invention is not limited to particular devices orbiological systems, which can, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting. As used in this specification and the appended claims, thesingular forms “a”, “an” and “the” include plural referents unless thecontent clearly dictates otherwise. Thus, for example, reference to “ananocrystal surface” or a “nanostructure surface” includes a combinationof two or more surfaces; reference to “a substituent” includes mixturesof substituents, and the like.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the invention pertains. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice for testing of the present invention, the preferredmaterials and methods are described herein. In describing and claimingthe present invention, the following terminology will be used inaccordance with the definitions set out below.

The term “conductive composition” as used herein refers to a monomeric(e.g. ligand), oligomeric or polymeric composition having the capacityfor electron conduction, hole conduction, or the ability to otherwiseundergo charge transfer.

The term “conjugated organic moiety” refers to an organic (i.e.,carbon-containing) molecule having two or more double bonds alternatingwith single bonds, and as such includes both linear and cyclicstructures.

The term “functionalized” as used herein refers to the presence of areactive chemical moiety or functionality.

The term “alkyl” as used herein refers to a chemical substituentconsisting of or containing the monovalent group C_(n)H_(2n), where n isan integer greater than zero.

The term “aryl” as used herein refers to a chemical substituentconsisting of or containing an aromatic group.

The terms “monodentate” and “multidentate” refers to a number ofattachment sites (monodentate having one site and multidentate havingmore than one site).

The term “polymerizable element,” as used herein, refers to a chemicalsubstituent or moiety capable of undergoing a self-polymerization and/orco-polymerization reaction, and as such, includes, but is not limitedto, vinyl derivatives, butadienes, trienes, tetraenes, diolefins,acetylenes, diacetylenes, styrene derivatives, as well as other reactivefunctional groups known to one of skill in the art.

The terms “oligomeric” and “polymeric” are used interchangeably hereinto refer to multimeric structures having more than one component monomeror subunit.

The term “matrix” as used herein refers to a material, often a polymericmaterial, into which a second material (e.g., a nanocrystallinecomposition) is embedded or surrounded. The matrix can be a conductivecomposition, a semiconductive composition, or a non-conductivecomposition.

A “nanostructure” is a structure having at least one region orcharacteristic dimension with a dimension of less than about 500 nm,e.g., less than about 200 nm, less than about 100 nm, less than about 50nm, or even less than about 20 nm. Typically, the region orcharacteristic dimension will be along the smallest axis of thestructure. Examples of such structures include nanowires, nanorods,nanotubes, branched nanocrystals, nanotetrapods, tripods, bipods,nanocrystals, nanodots, quantum dots, nanoparticles, branched tetrapods(e.g., inorganic dendrimers), and the like. Nanostructures can besubstantially homogeneous in material properties, or in certainembodiments can be heterogeneous (e.g. heterostructures). Nanostructurescan be, e.g., substantially crystalline, substantially monocrystalline,polycrystalline, amorphous, or a combination thereof. In one aspect,each of the three dimensions of the nanostructure has a dimension ofless than about 500 nm, e.g., less than about 200 nm, less than about100 nm, less than about 50 nm, or even less than about 20 nm.Nanostructures can comprise one or more surface ligands (e.g.,surfactants).

The terms “crystalline” or “substantially crystalline”, when used withrespect to nanostructures, refer to the fact that the nanostructurestypically exhibit long-range ordering across one or more dimensions ofthe structure. It will be understood by one of skill in the art that theterm “long range ordering” will depend on the absolute size of thespecific nanostructures, as ordering for a single crystal cannot extendbeyond the boundaries of the crystal. In this case, “long-rangeordering” will mean substantial order across at least the majority ofthe dimension of the nanostructure. In some instances, a nanostructurecan bear an oxide or other coating, or can be comprised of a core and atleast one shell. In such instances it will be appreciated that theoxide, shell(s), or other coating need not exhibit such ordering (e.g.it can be amorphous, polycrystalline, or otherwise). In such instances,the phrase “crystalline,” “substantially crystalline,” “substantiallymonocrystalline,” or “monocrystalline” refers to the central core of thenanostructure (excluding the coating layers or shells). The terms“crystalline” or “substantially crystalline” as used herein are intendedto also encompass structures comprising various defects, stackingfaults, atomic substitutions, and the like, as long as the structureexhibits substantial long range ordering (e.g., order over at leastabout 80% of the length of at least one axis of the nanostructure or itscore). In addition, it will be appreciated that the interface between acore and the outside of a nanostructure or between a core and anadjacent shell or between a shell and a second adjacent shell maycontain non-crystalline regions and may even be amorphous. This does notprevent the nanostructure from being crystalline or substantiallycrystalline as defined herein.

The term “monocrystalline” when used with respect to a nanostructureindicates that the nanostructure is substantially crystalline andcomprises substantially a single crystal. When used with respect to ananostructure heterostructure comprising a core and one or more shells,“monocrystalline” indicates that the core is substantially crystallineand comprises substantially a single crystal.

A “nanocrystal” is a nanostructure that is substantiallymonocrystalline. A nanocrystal thus has at least one region orcharacteristic dimension with a dimension of less than about 500 nm,e.g., less than about 200 nm, less than about 100 nm, less than about 50nm, or even less than about 20 nm. Typically, the region orcharacteristic dimension will be along the smallest axis of thestructure. Examples of such structures include nanowires, nanorods,nanotubes, branched nanowires, nanotetrapods, nanotripods, nanobipods,nanocrystals, nanodots, quantum dots, nanoparticles, nanoribbons, andthe like. Nanostructures can be substantially homogeneous in materialproperties, or in certain embodiments can be heterogeneous (e.g.heterostructures). Optionally, a nanocrystal can comprise one or moresurface ligands (e.g., surfactants). The nanocrystal is optionallysubstantially single crystal in structure (a “single crystalnanostructure” or a “monocrystalline nanostructure”). Whilenanostructures for use in the present invention can be fabricated fromessentially any convenient material or material, preferably thenanostructure is prepared from an inorganic material, e.g., an inorganicconductive or semiconductive material. A conductive or semi-conductivenanostructure often displays 1-dimensional quantum confinement, e.g., anelectron can often travel along only one dimension of the structure.Nanocrystals can be substantially homogeneous in material properties, orin certain embodiments can be heterogeneous (e.g. heterostructures). Theterm “nanocrystal” is intended to encompass substantiallymonocrystalline nanostructures comprising various defects, stackingfaults, atomic substitutions, and the like, as well as substantiallymonocrystalline nanostructures without such defects, faults, orsubstitutions. In the case of nanocrystal heterostructures comprising acore and one or more shells, the core of the nanocrystal is typicallysubstantially monocrystalline, but the shell(s) need not be. Thenanocrystals can be fabricated from essentially any convenient materialor materials.

A “nanowire” is a nanostructure that has one principle axis that islonger than the other two principle axes. Consequently, the nanowire hasan aspect ratio greater than one; nanowires of this invention have anaspect ratio greater than about 1.5 or greater than about 2. Shortnanowires, sometimes referred to as nanorods, typically have an aspectratio between about 1.5 and about 10. Longer nanowires have an aspectratio greater than about 10, greater than about 20, greater than about50, or greater than about 100, or even greater than about 10,000. Thediameter of a nanowire is typically less than about 500 nm, preferablyless than about 200 nm, more preferably less than about 150 nm, and mostpreferably less than about 100 nm, about 50 nm, or about 25 nm, or evenless than about 10 nm or about 5 nm. The nanowires employed in thepresent invention can be substantially homogeneous in materialproperties, or in certain embodiments can be heterogeneous (e.g.nanowire heterostructures). The nanowires can be fabricated fromessentially any convenient material or materials. The nanowires cancomprise “pure” materials, substantially pure materials, doped materialsand the like, and can include insulators, conductors, andsemiconductors. Nanowires are typically substantially crystalline and/orsubstantially monocrystalline. Nanowires can have a variable diameter orcan have a substantially uniform diameter, that is, a diameter thatshows a variance less than about 20% (e.g., less than about 10%, lessthan about 5%, or less than about 1%) over the region of greatestvariability and over a linear dimension of at least 5 nm (e.g., at least10 nm, at least 20 nm, or at least 50 nm). Typically the diameter isevaluated away from the ends of the nanowire (e.g. over the central 20%,40%, 50%, or 80% of the nanowire). A nanowire can be straight or can bee.g. curved or bent, over the entire length of its long axis or aportion thereof. In certain embodiments, a nanowire or a portion thereofcan exhibit two- or three-dimensional quantum confinement. Nanowiresaccording to this invention can expressly exclude carbon nanotubes, and,in certain embodiments, exclude “whiskers” or “nanowhiskers”,particularly whiskers having a diameter greater than 100 nm, or greaterthan about 200 nm. Nanorods, nanowires and other nanostructures aredescribed in detail in WO 04/022637, the contents of which areincorporated herein in their entirety.

An “aspect ratio” is the length of a first axis of a nanostructuredivided by the average of the lengths of the second and third axes ofthe nanostructure, where the second and third axes are the two axeswhose lengths are most nearly equal each other. For example, the aspectratio for a perfect rod would be the length of its long axis divided bythe diameter of a cross-section perpendicular to (normal to) the longaxis.

The “band gap difference” between HOMO and LUMO states refers the energynecessary make the transition across the “band gap” region separatingthe valence and conduction bands.

CONDUCTIVE COMPOSITION

In one aspect, the present invention provides conductive compositionsfor modification of charge transport, e.g., across ananostructure-containing matrix. The compositions are used inconjunction with a nanostructure composition, such as ananocrystal-containing photovoltaic matrix. Alternatively, theconductive compositions of the present invention can be employed withnon-nanoscale semiconductive components. The conductive compositions ofthe present invention typically include three basic components: a coreelement or “body structure,” a “head group” coupled to the bodystructure at a first position and capable of associating with ananostructure surface, and a “tail” group coupled to the body structureat a second position. In addition, the conductive composition canoptionally include one or more “sidechain” elements coupled to the bodystructure at additional locations (i.e. third position, fourth position,etc).

Each of these components is described in greater detail below. Theelements comprising the conductive compositions of the present inventionwork together to provide a conductive coating on the bound surface(e.g., a nanocrystal surface), or a polymeric matrix encompassing thesemiconductor surface, thereby permitting and/or enhancing electronand/or hole transfer. For example, when light impinges upon ananocrystal component of an optoelectric device (such as a photovoltaicdevice), the photon is absorbed by the nanocrystal creating an excitonwithin the nanocrystal. By conducting the electron away from the hole,one creates an electric potential that can be exploited. The conductivecompositions (e.g., ligand-type coatings and/or polymeric matrices) ofthe present invention assist in the generation of the electricpotential. The assistance can be, for example, via donation (injection)of an electron to the nanocrystal or other semiconductive material, orvia conduction (extraction) of the hole away from the nanocrystal orsemiconductor. In a preferred embodiment, the charge mobility (movementof the electrons) enhanced by the conductive compositions of the presentinvention is sufficiently fast so as to avoid recombination of theelectron and hole. A further discussion of charge separation andconduction as it relates to the conductive compositions and relateddevices of the present invention (e.g., photovoltaic devices and LEDs)can be found in WO 04/023527.

Body Structure

A conjugated organic moiety is selected for the core of the conductivecomposition. This conjugated moiety typically is either a conjugatedalkyl moiety or a conjugated aryl moiety. Exemplary body structures foruse in the compositions of the present invention include, but are notlimited to, phenylene, thiophene, ethene, ethyne, aniline, pyridine,phenanthralene, various alkenyl structures, and the like. In someembodiments, a polynuclear aromatic moiety (e.g., a polynuclear aromatichydrocarbon, or PAH) is employed as the conjugated organic moiety.Exemplary PAH compounds include, but are not limited to, anthracene,benzo[a]anthracene, chrysene, fluorene, perylene, naphthalene,acenaphthene, acenaphthalene, phenanthrene, pyrene, benzo[a]pyrene, andthe like.

In one embodiment, the function of the conjugated organic moiety is toprovide hole transport from the crystal to the polymer matrix (andoptionally, to an electrode or electrode surface of, e.g., aphotovoltaic device). Movement of the hole along this conjugated“backbone” of the conductive composition (e.g., charge transport) isenhanced by selecting or matching the electronic characteristics of thebody structure, such that hole transport from the nanocrystal to thepolymer matrix is favored over electron transport (i.e., the bodystructure element of the conductive composition has a higher HOMO energylevel than the nanocrystal and a lower HOMO level than the surroundingpolymer). Alternatively, the conductive composition of the presentinvention can be modularly designed for enhanced electron transport.

In some embodiments of the present invention, the body structure is anoligomeric or polymeric structure, such as poly(phenylene),poly(thiophene), poly(ethene), poly(ethyne), poly(aniline),poly(fluorene), poly(pyridine), poly (PAH), and the like. The extent ofpolymerization can range from just a few repeating elements (e.g., 2, 3,4, 5, 6, etc) or longer polymers (e.g., having tens of repeating units).Furthermore, additional or alternative oligomeric or polymericconjugated structures known to one of skill in the art can also beemployed as the body structure of the present composition.

Head Group

The conductive compositions of the present invention further include a“head group” coupled to the body structure at a first position on theconjugated organic moiety. In the unbound configuration, the head groupis a functionalized element capable of binding to a nanostructuresurface. Optionally, the head group is a bound head group (e.g., forembodiments in which the composition is associated with thenanostructure). Both the bound and functionalized chemical structuresare considered “head groups” in the present invention.

Exemplary chemical moieties for use as functionalized head groups in thepresent invention include, but are not limited to, phosphonic acid,phosphinic acid, carboxylic acid, amine, amine oxide, phosphine,phosphine oxide, phosphonate, phosphonite, hydroxyl, and thiol moieties.

Alternatively, nitrogen-containing aromatic compounds or heterocycles(e.g., imidazoles, benzoimidazoles, pyridines, pyrimidines, purines, orquinolines) can also be used as nanostructure-binding head groupmoieties in the compositions of the present invention. Exemplarycompounds include, but are not limited to, derivatives of2-methylpyridine, 3-ethylpyridine, 4-chloropyridine, collidine,dimethylquinoline, and other compounds commonly used as nanostructuregrowth terminators.

In some embodiments, the functionalized (or bound) head group is amonodentate structure (e.g., a single moiety capable of binding thenanostructure). In an alternate embodiment, the head group is amultidentate structure capable of a plurality of interactions with thenanostructure surface.

Optionally, the head group element includes one or more polymerizableelements. The polymerizable element can be employed, in someembodiments, to prepare conductive compositions having a plurality ofhead group modules attached (e.g., linearly) to a single body structure.One such composition would have the formula (H_(x))-B-T, in which xcopies of the head moiety (H) are attached to a body structure (B) andtail group (T), e.g., during synthesis of the conjugated composition.Alternatively, the polymerizable elements on the head group are used topolymerize proximal elements of the conductive composition. Thepolymerization can occur between two head groups, or between a headgroup and another element of the conductive composition (e.g., a tailgroup or optional sidechain). An exemplary composition of this nature isdescribed by the formula (H-B-T)_(n), where n represents the number (oraverage number) of member compositions in the polymer. While theproximal elements are preferably polymerized after attachment to thenanostructure surface, in some polymeric embodiments, the elements arepolymerized prior to exposure to the nanostructure.

Tail Group

The conductive compositions of the present invention also include a tailgroup coupled to the body structure at a second position (tail position)on the conjugated organic moiety. Either conducting or a non-conductingchemical structures can be employed as tail groups in the presentinvention. Typically, the tail group is an alkyne structure composed ofn carbons (where n is equal to 3-22); however, even larger alkynestructures (having greater than 22 carbons) are also contemplated foruse in the compositions of the present invention. Exemplary alkynes foruse in the present invention include, but are not limited to, 1-propyne,1-butyne, 1-pentyne, 1-hexyne, 1-heptyne, 1-octyne, 1-nonyne, and1-decyne. Optionally, any alkyne comprising between 3 and 22 carbons (orlonger) can be employed as a tail group in the present invention.Alternatively, other moieties having “rigid” elements, such methylene,aryl, acetylene and alkene groups, can be used as tail groups in thepresent invention. The more rigid constituents can be used to producemore conductive compositions (and, in the embodiment in which theconductive compositions include polymerizable elements, a morethermodynamically predictable product).

The alkyne structure can be linear or branched, depending in part uponthe particular system in which the composition will be employed. Forexample, in some embodiments, the increased steric hindrances incurredby branched alkynyl chain employed as tail groups can affect theconjugation of the conductive composition (e.g., by altering thepositioning of an aryl component of the body structure). Changes in themolecule-molecule and polymer-molecule order, stacking and packing canalso have an effect on the electronic properties and charge transportcapabilities. In a preferred embodiment, linear (e.g., non-branched)alkyl chains are preferred for use as tail group moieties.

In some embodiments, the tail group further includes a thiophene moiety;when present, the thiophene is preferably positioned between the alkynemoiety and the body structure (e.g., the thiophene couples the tailgroup to the conjugated organic species at the second position of thebody structure).

Optionally, the tail group further includes a chemical functionalitycapable of binding to the nanostructure surface. As described for thehead group element, the tail group can be either a monodentate or amultidentate structure. When present, the nanostructure-bindingfunctionality incorporated into the tail group is optionally used, forexample, for coupling to a second nanostructure surface (e.g., forming abridging composition between proximal nanocrystals).

For example, in a further embodiment, the conductive composition of thepresent invention can include a di-alkyne or di-alkene tail groupsubstituent having the formula CC—(CH2)_(n)—CC, in which CC representseither double or triple bonded carbon atoms (flanking an alkyl chain, inthis embodiment). Optionally, a nanostructure binding moiety (e.g.,phosphanate) is incorporated within the tail element, e.g., at a sitedistal to the site for attachment to the body structure (as representedby the formula (OH)₂P(O)—CC—(CH2)_(n)—CC—). The presence of multiplealkyne or alkene moieties within the tail group module can be used toalter the geometry of the tail and can affect the binding of the headgroup. The nanostructure binding moiety incorporated into the tail groupcan be the same or different moiety as present in the head group.Optionally, the nanostructure binding moiety incorporated into the tailgroup can be used to bind to the same nanostructure as the head group,or it can be coupled to an adjacent crystal (i.e., linking thecrystals). In a further embodiment, different nanostructure bindingmoieties favoring attachment to different nanostructure structures areemployed in the multi-dentate conductive compositions of the presentinvention (forming, e.g., an asymmetric bidentate conductivecomposition). Such compositions can be employed, e.g., to alignnanostructures within a two crystal system.

In another embodiment of the present invention, the tail group includesone or more polymerizable elements. As described previously, thepolymerizable element can be employed, in some embodiments, to prepareconductive compositions having a plurality of tail group modulesattached (e.g., linearly) to a single body structure. One suchcomposition would have the formula H-B-(T_(z)), in which z copies of thetail moiety are attached to the body structure. Alternatively, thepolymerizable elements on the tail group are used to polymerize proximalelements of the conductive composition, similar to that described forthe optional polymerizable elements on the head group (e.g., between twotail groups, or between a tail group and another element of theconductive composition). While the proximal elements are preferablypolymerized after attachment to the nanostructure surface, thepolymerizable elements can be coupled prior to exposure of thecomposition to the nanostructure.

Optional Sidechains

The body structure optionally includes one or more sidechains coupled tothe conjugated organic species. Optionally, the conductive compositionincludes two, three, or four side chains (although additional sidechainsare conceivable given an appropriately-configured body structure).

Changes in sidechain composition can be used, e.g., to alter thesolubility of the conductive composition, for electronic adjustment ofthe composition, and/or for polymerization purposes. For example, thesidechain can optionally include a carbonyl ester moiety; as a result ofthe electron-withdrawing property of the carbonyl, the conductivecomposition containing this sidechain will enhance (favor) electrontransfer. Alternatively, incorporation of a simple alkyl chain as thesidechain substituent will favor hole transfer by virtue of the electrondonating nature of the substituent.

Either conducting or a non-conducting chemical structures can beemployed as sidechains in the present invention. Conducting chemicalstructures have the added advantage of extending the conjugation of theorganic core structure.

In a preferred embodiment, the sidechains are O-linked or N-linkedchemical structures (e.g., are coupled to an existing hydroxyl or aminegroup on the body structure). Exemplary sidechain moieties for use inthe present invention include, but are not limited to, an O-linked orN-linked hexane moiety, an O-linked or N-linked 2-ethylhexyl moiety, anO-linked or N-linked octyl moiety, an O-linked or N-linked decyl moiety.Optionally, any O-linked or N-linked alkyl moiety comprising between 5and 22 (or more) carbons can be used as a sidechain component (includingalkane, alkene, alkyne, vinyl, and aryl structures).

As noted above, the chemical substituents employed as sidechain elementscan optionally be either electron donating groups or electronwithdrawing groups, depending upon the intended use. For example, inembodiments in which the modification of charge transport involveselectron transport, electron withdrawing groups are preferred; incontrast, for transport of the “holes”, electron donating groupsfunction better.

In a preferred embodiment, a first sidechain is coupled to the bodystructure at a first sidechain position (i.e., a third position on theconjugated organic species), and a second sidechain is coupled to thebody structure at a second sidechain position (i.e., a fourth positionon the conjugated organic species). The sidechains can be identicalchemical moieties, or they can differ in their chemical structure.Optionally, the side chain(s) can have the same chemical composition asthe head group or the tail group.

In some embodiments of the present invention, the sidechain substituentis matched functionally and/or electronically to a matrix composition ofthe nanostructure-containing matrix. For example, the sidechainoptionally can include functionalities which interact with matrixfunctionalities (e.g., affinity binding, ionic interactions, covalentinteractions and/or bond formation, and the like). Alternatively, thesidechain elements can be used to affect the electronic signature of thesurrounding matrix. For example, the distance between the conductivecomposition (e.g., ligand) and the polymer matrix, the aryl groupmatrix-matrix stacking distance and packing order, and/or thematrix-ligand stacking distance and packing can be altered or controlledby varying the sidechain element of the conductive composition, therebyaffecting the interaction of the side chain with the surrounding matrixand modifying the electronic signature of thematrix-ligand-nanostructure system.

The length of the alkyl portion of the sidechain can be used toinfluence solubility; as such and can be any length or branching scheme.Both solubility and electronic properties can be adjusted simultaneously(or independently) via various combinations of the sidechain elements.

In another embodiment of the present invention, the side group includesone or more polymerizable elements. In some embodiments of thecompositions of the present invention, the polymerizable elements on thesidechains interact with each other, thereby crosslinking individualmembers of the conductive composition to form a polymeric conductivecomposition. The polymerization can occur between sidechains on adjacentconductive compositions, or between a sidechain and another element ofthe conductive composition (e.g., a head group or tail group). While theproximal elements are preferably polymerized after attachment to thenanostructure surface, in some embodiments, the elements are polymerizedprior to exposure to the nanostructure.

Alternatively, the polymerizable element can be employed to prepareextended sidechain components (e.g., as a means for coupling additionalmoieties to the conductive composition).

Exemplary chemical moieties which can be incorporated as sidechainelements include, but are not limited to, alkyl (e.g., alkane, alkene,or alkyne) chains ranging in length from one carbon to 22 carbons (orlonger), carbonyls, acrylates, methacrylates, cinnamic esters, and thelike. In some embodiments, the sidechain element includes a carbonylester having a diene moiety, such as butadiene (e.g.,O—C(O)—(CH₂)_(n)-butadiene). The diene moiety, which can be positionedanywhere along the esterified alkyl chain (e.g., near the carbonyl,towards the middle of the alkyl chain, at the terminus distal to theO-linkage, etc.). can then optionally be polymerized, for example, withlight via a 2+2 or 4+4 polymerization reaction. See, for example, Paleos(ed.) Polymerization in Organized Media (Gordon and Breach SciencePublishers, Philadelphia, 1992.

Furthermore, the modular approach to the chemical synthesis of theconductive compositions of the present invention (e.g., convergentperiphery modification) lends itself to a number of combinations ofvarious head moieties, tail groups, and optional side chain elements.

Exemplary conductive compositions of the present invention are providedin Table 1 below, and in the figures and examples. TABLE 1 Exemplaryconductive compositions  5b

16

21b

25

28

31

36

41a

43

46

50

POLYMER EMBODIMENT

As noted above, one or more of the constituents of the conductivecompositions can optionally include polymerizable elements. The presentinvention also provides oligomeric and polymer conductive compositionsfor use with nanostructures. The oligomeric and/or polymericcompositions can be used as either coatings on nanostructures, or as thematrix into which the nanostructure in embedded. Optionally, thenanostructure is coated with a first conductive composition of thepresent invention, and the embedded in an additional (e.g., second)polymeric conductive composition. In an additional embodiment, differenttypes of nanostructures (e.g., p-type and n-type nanocrystals) arecoupled or crosslinked within a matrix via the conductive compositionsof the present invention.

One way to accomplish efficient charge transport is by designing anelectronic “stairway” for both holes and electrons via bandgapadjustment, where the matrix polymer may have a highest occupiedmolecular orbital (HOMO) level slightly higher than the HOMO of ananostructure-bound conductive composition ligand (which itself has aHOMO level higher than that of the nanostructure). Since theenergetically favored pathway for hole transport is from lower to higherHOMO levels, this design will promote hole transport from thenanostructure to the ligand to the polymer to the electrode. Conversely,the matrix polymer can have a LUMO (lowest unoccupied molecular orbital)level slightly lower than the ligand LUMO, and the ligand LUMO may belower than the crystal LUMO level. This will favor electron transportfrom the polymer via the ligand and nanostructure to the electrode. Wehave performed model calculations of the bandgap, HOMO and LUMO levelsof the ligands and polymer, showing that this can be achieved by tuningboth the ligand and the polymer to meet these requirements. One way toaccomplish this is to use similar components for the polymer and theoligomer so the electronic signatures of each are similar but can betuned slightly to afford the appropriate electronic stairway for holeand electron transport, respectively.

Polymerizable Elements

Any of the elements of the of the conductive compositions of presentinvention (head group, body structure, tail group, and/or sidechains)can include one or more of the polymerizable elements. Exemplarychemical substituents which can be incorporated into the composition,but are not limited to, vinyl derivatives, butadienes, trienes,tetraenes, diolefins, acetylenes, diacetylenes, styrene derivatives andthe like. Exemplary sidechain substituents and/or derivatives (andmechanisms for coupling or crosslinking) are provided, for example, inPaleos, supra, and Kraft et al. (1998) “Electroluminescent ConjugatedPolymers—Seeing Polymers in a New Light” Angew Chem. Int. Ed.37:402-428.

For the crosslinking reaction, the polymerizable element can be situatedat the end of the selected element, or it an be internal (e.g., amidstan alkyl chain substituent). Various polymerization schemes arecontemplated in the present invention, including, but not limited to,polyaddition reactions (thermal, photo-induced or radiation-induced);polycondensations; oxidative couplings, and the like. A preferredpolymerization scheme is vinyl polymerization of sidechain substituentsin adjacent conductive compositions.

Polymeric Compositions

In a preferred embodiment, the polymeric conductive compositions of thepresent invention typically have the structure [H_(x)-B_(y)-T_(z)]_(n),where H represents the head group, B represents the body structure, andT represents the tail group. The subscripts x, y and z represent thenumber of repeating elements (of head group, body structure, or tailgroup, respectively) present in a “monomeric” subunit of the polymer,while the value for n provides for the number of monomeric units presentin the polymer; these values are integers. An embodiment in which x, y,z and n all equal 1 is equivalent to the monomeric conductivecomposition as previously described. Thus, for the polymeric compositionof the invention, the sum of these integers (x+y+z+n) is an integergreater than 4 (i.e., 5 or greater). FIG. 8 depicts exemplary polymericconductive compositions of the present invention in which multiple bodystructure components are depicted with similar or dissimilar sidechainelements attached. N is an integer, ranging in value from 1 (i.e., themonomeric form of the composition) to 10 or more. (e.g., to 15, 2, 25,50, 100, etc.)

Sidechains can also be present, coupled to one or more of the bodystructures in the polymeric conductive composition; these optionalsidechains are not depicted in the formula independent of body structureB, but are optionally present. In some polymeric embodiments of thepresent invention, the sidechain moiety is present on a majority of thebody structures present (i.e., on at least 50% of the body structures);in further embodiments, the sidechain is present on at least 75%, 90%,95%, 99% or essentially all of the member body structures. Optionally,these sidechain moieties can be the same chemical functionality;alternatively, the composition of the sidechain varies from bodystructure to body structure. For example, in one embodiment, the bodystructures of the polymer alternate between attachment of two differentsidechain moieties. In another embodiment, the plurality of sidechainspresent in the composition is a random mixture of two, three, four, ormore chemical substituents.

When in use (e.g., in the presence of nanostructures), at least one headgroup moiety of the polymeric conductive composition is bound to thenanostructure surface. Optionally, a majority of the head groups (e.g.,at least 50%, about 75%, about 90%, about 95%, about 99%, or essentiallyall of the head groups) are in the bound form. As noted in a previoussection, polymerization can be performed either prior to or afterbinding of the conductive composition to the nanostructure structure;furthermore, the polymer can be partially crosslinked in an initialstep, and further crosslinked upon interaction with the nanostructurestructure. Thus, compositions including the conductive composition orpolymer in combination with the nanostructure structure (e.g.,nanostructure-containing matrices) are also contemplated in the presentinvention.

NANOSTRUCTURE-MATRIX

The conductive compositions would also be useful in chargeinjection/extraction from other, non nanoscale surfaces, e.g., bulkcrystalline materials, etc. Thus, while nanostructures and othernanoscale compositions are preferred embodiment, the conductivecompositions described herein can be used for chargeinjection/extraction from other, non nanoscale surfaces, e.g., bulkcrystalline materials, etc., and as such are not limited to eithernanoscale and non-nanoscale (e.g., bulk crystalline) assemblies. In oneembodiment, the nanostructure-containing matrices comprise ananostructure having an exterior surface, wherein a portion of thenanostructure exterior surface is cojoined to a conductive compositionof the present invention; and a matrix component positioned proximal tothe conjugated exterior surface of the nanostructure. The conductivecomposition employed in the nanostructure-containing matrices can beeither a monomeric composition or a polymeric version, e.g., coating thenanostructure. The matrix component can be either a conductive matrix ora nonconductive matrix, depending on the use envisioned for the product.Exemplary matrices for use in the present invention include, but are notlimited to, poly-3-hexylthiophene (P3HT), poly(p-phenylene vinylene(PPV), and poly(2-methoxy, 5 ethyl(2′hexyloxy)p-phenylene vinylene(MEH-PPV).

In another embodiment, the nanostructure-containing matrices of thepresent invention include, but are not limited to, a nanostructure and amatrix composition positioned proximal to an exterior surface of thenanostructure, wherein the matrix composition comprises a polymerizedembodiment of the conductive compositions of the present invention. Forexample, the conductive polymer having the structure[T_(x)-B_(y)-H_(z)]_(n) is contemplated, wherein H comprises at leastone functionalized head group capable of binding to a nanostructuresurface; wherein B comprises a body structure comprising one or moreconjugated organic moieties, wherein a first conjugated organic moietyis coupled to the at least one functionalized head group; wherein Tcomprises at least one tail group coupled to the body structure; andwherein x, y, z and n independently comprise integers equal to orgreater than 1. The polymerization is achieved via crosslinking ofpolymerizable units on the elements (for example, the sidechain) of thecomposition.

In a further embodiment of the present invention, the conductivepolymeric composition of the matrix is covalently coupled to a furtherconductive composition applied to the nanostructure. In a preferredembodiment, this additional conductive composition is functionallyand/or electronically matched to one or more components of theconductive polymeric matrix.

Matrices

A wide variety of nanostructure-compatible polymers are known to thoseof skill in the art (see e.g., Demus et al. (ed.) 1998 Handbook ofLiquid Crystals Volumes 1-4, John Wiley and Sons, Inc., Hoboken, N.J.);Brandrup (ed.) 1999 Polymer Handbook, (John Wiley and Sons, Inc.);Harper 2002 Handbook of Plastics, Elastomers, and Composites, 4thedition (McGraw-Hill, Columbus, Ohio); and Kraft et al. (1998) Angew.Chem. Int. Ed. 37:402-428. While either conductive or nonconductivepolymers can be used in conjunction with the conductive compositions ofthe present invention, preferred embodiments of the present inventionemploy conductive polymers.

Exemplary polymers for use in the present invention include, but are notlimited to, thermoplastic polymers (e.g., polyolefins, polyesters,polysilicones, polyacrylonitrile resins, polystyrene resins, polyvinylchloride, polyvinylidene chloride, polyvinyl acetate, orfluoroplastics); thermosetting polymers (e.g., phenolic resins, urearesins, melamine resins, epoxy resins, polyurethane resins); engineeringplastics (e.g., polyamides, polyacrylate resins, polyketones,polyimides, polysulfones, polycarbonates, polyacetals); and liquidcrystal polymers, including main chain liquid crystal polymers (e.g.,poly(hydroxynapthoic acid)) and side chain liquid crystal polymers(e.g., poly[n-((4′(4″-cyanphenyl)phenoxy)alkyl)vinyl ether]). Certainembodiments include conductive organic polymers; see e.g. T. A.Skatherin (ed.) 1986 Handbook of Conducting Polymers I. (Marcel Dekker,New York). Examples of conductive polymers for use as matrices of thepresent invention include, but are not limited to,poly(3-hexylthiophene) (P3HT), poly[2-methoxy,5-(2′-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV), poly(p-phenylenevinylene) (PPV), and polyaniline.

Nanostructures

As noted previously, structures for use in the present inventioninclude, but are not limited to nanoscale and non-nanoscale (e.g., bulkcrystalline) assemblies. Nanostructures, such as nanocrystals,nanowires, nanorods, nanoparticles and the like, can be fabricated by anumber of mechanisms known to one of skill in the art. Furthermore,their size can be controlled by any of a number of convenient methodsthat can be adapted to different materials. For example, synthesis ofnanocrystals of various composition is described in, e.g., Peng et al.(2000) “Shape control of CdSe nanocrystals”0 Nature 404:59-61; Puntes etal. (2001) “Colloidal nanocrystal shape and size control: The case ofcobalt” Science 291:2115-2117; U.S. Pat. No. 6,306,736 to Alivisatos etal. (Oct. 23, 2001) entitled “Process for forming shaped group III-Vsemiconductor nanocrystals, and product formed using process”; U.S. Pat.No. 6,225,198 to Alivisatos et al. (May 1, 2001) entitled “Process forforming shaped group II-VI semiconductor nanocrystals, and productformed using process”; U.S. Pat. No. 5,505,928 to Alivisatos et al.(Apr. 9, 1996) entitled “Preparation of III-V semiconductornanocrystals”; U.S. Pat. No. 5,751,018 to Alivisatos et al. (May 12,1998) entitled “Semiconductor nanocrystals covalently bound to solidinorganic surfaces using self-assembled monolayers”; U.S. Pat. No.6,048,616 to Gallagher et al. (Apr. 11, 2000) entitled “Encapsulatedquantum sized doped semiconductor particles and method of manufacturingsame”; and U.S. Pat. No. 5,990,479 to Weiss et al. (Nov. 23, 1999)entitled “Organo luminescent semiconductor nanocrystal probes forbiological applications and process for making and using such probes.”

Growth of nanowires having various aspect ratios, including nanowireswith controlled diameters, is described in, e.g., Gudiksen et al (2000)“Diameter-selective synthesis of semiconductor nanowires” J. Am. Chem.Soc. 122:8801-8802; Cui et al. (2001) “Diameter-controlled synthesis ofsingle-crystal silicon nanowires” Appl. Phys. Lett. 78: 2214-2216;Gudiksen et al. (2001) “Synthetic control of the diameter and length ofsingle crystal semiconductor nanowires” J. Phys. Chem. B 105:4062-4064;Morales et al. (1998) “A laser ablation method for the synthesis ofcrystalline semiconductor nanowires” Science 279:208-211; Duan et al.(2000) “General synthesis of compound semiconductor nanowires” Adv.Mater. 12:298-302; Cui et al. (2000) “Doping and electrical transport insilicon nanowires” J. Phys. Chem. B 104:5213-5216; Peng et al. (2000),supra; Puntes et al. (2001), supra; U.S. Pat. No. 6,225,198 toAlivisatos et al., supra; U.S. Pat. No. 6,036,774 to Lieber et al. (Mar.14, 2000) entitled “Method of producing metal oxide nanorods”; U.S. Pat.No. 5,897,945 to Lieber et al. (Apr. 27, 1999) entitled “Metal oxidenanorods”; U.S. Pat. No. 5,997,832 to Lieber et al. (Dec. 7, 1999)“Preparation of carbide nanorods”; Urbau et al. (2002) “Synthesis ofsingle-crystalline perovskite nanowires composed of barium titanate andstrontium titanate” J. Am. Chem. Soc., 124, 1186; Yun et al. (2002)“Ferroelectric Properties of Individual Barium Titanate NanowiresInvestigated by Scanned Probe Microscopy” Nano Letters 2, 447; andpublished PCT application nos. WO 02/17362, and WO 02/080280.

Growth of branched nanowires (e.g., nanotetrapods, tripods, bipods, andbranched tetrapods) is described in, e.g., June et al. (2001)“Controlled synthesis of multi-armed CdS nanorod architectures usingmonosurfactant system” J. Am. Chem. Soc. 123:5150-5151; and Manna et al.(2000) “Synthesis of Soluble and Processable Rod-,Arrow-, Teardrop-, andTetrapod-Shaped CdSe Nanocrystals” J. Am. Chem. Soc. 122:12700-12706.Synthesis of nanoparticles is described in, e.g., U.S. Pat. No.5,690,807 to Clark Jr. et al. (Nov. 25, 1997) entitled “Method forproducing semiconductor particles”; U.S. Pat. No. 6,136,156 to El-Shall,et al. (Oct. 24, 2000) entitled “Nanoparticles of silicon oxide alloys”;U.S. Pat. No. 6,413,489 to Ying et al. (Jul. 2, 2002) entitled“Synthesis of nanometer-sized particles by reverse micelle mediatedtechniques”; and Liu et al. (2001) “Sol-Gel Synthesis of Free-StandingFerroelectric Lead Zirconate Titanate Nanoparticles” J. Am. Chem. Soc.123:4344. Synthesis of nanoparticles is also described in the abovecitations for growth of nanocrystals, nanowires, and branched nanowires,where the resulting nanostructures have an aspect ratio less than about1.5.

Synthesis of core-shell nanostructure heterostructures are described in,e.g., Peng et al. (1997) “Epitaxial growth of highly luminescentCdSe/CdS core/shell nanocrystals with photostability and electronicaccessibility” J. Am. Chem. Soc. 119:7019-7029; Dabbousi et al. (1997)“(CdSe)ZnS core-shell quantum dots: Synthesis and characterization of asize series of highly luminescent nanocrystallites” J. Phys. Chem. B101:9463-9475; Manna et al. (2002) “Epitaxial growth and photochemicalannealing of graded CdS/ZnS shells on colloidal CdSe nanorods” J. Am.Chem. Soc. 124:7136-7145; and Cao et al. (2000) “Growth and propertiesof semiconductor core/shell nanocrystals with InAs cores” J. Am. Chem.Soc. 122:9692-9702. Similar approaches can be applied to growth of othercore-shell nanostructures. See, for example, U.S. Pat. No. 6,207,229(Mar. 27, 2001) and U.S. Pat. No. 6,322,901 (Nov. 27, 2001) to Bawendiet al. entitled “Highly luminescent color-selective materials”.

Growth of homogeneous populations of nanowires, including nanowireheterostructures in which the different materials are distributed atdifferent locations along the long axis of the nanowire is described in,e.g., published PCT application nos. WO 02/17362, and WO 02/080280;Gudiksen et al. (2002) “Growth of nanowire superlattice structures fornanoscale photonics and electronics” Nature 415:617-620; Bjork et al.(2002) “One-dimensional steeplechase for electrons realized” NanoLetters 2:86-90; Wu et al. (2002) “Block-by-block growth ofsingle-crystalline Si/SiGe superlattice nanowires” Nano Letters 2,83-86; and U.S. patent application 60/370,095 (Apr. 2, 2002) toEmpedocles entitled “Nanowire heterostructures for encodinginformation.” Similar approaches can be applied to growth of otherheterostructures.

In certain embodiments, the collection or population of nanostructuresis substantially monodisperse in size and/or shape. See e.g., U.S.patent application 20020071952 by Bawendi et al entitled “Preparation ofnanocrystallites.”

The diameter of the inorganic nanowires can be varied, for example, tocontrol the wavelength emitted by fluorescent nanowires. The diameter ofthe nanowires is preferably between about 2 nm and about 100 nm, morepreferably between about 2 nm and about 5 nm or between about 10 nm andabout 50 nm. The length of the nanowires can also be varied. In certainembodiments, the inorganic nanowires have an aspect ratio between about10 and about 10,000 (e.g., between about 20 and about 10,000, betweenabout 50 and about 10,000, or between about 100 and about 10,000).

The nanowires can be fabricated of essentially any convenient material(e.g., a semiconducting material, a ferroelectric material, a metal,etc.) and can comprise essentially a single material or can beheterostructures.

The nanostructures employed in the nanostructure-containing matrices ofthe present invention can be fabricated from essentially any convenientmaterials. E.g., the nanocrystals can comprise an inorganic materials,e.g., a semiconducting material, for example a material comprising afirst element selected from group2 or from group 12 of the periodictable and a second element selected from group 16 (e.g., ZnS, ZnO, ZnSe,ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, MgS, MgSe, MgTe, CaS, CaSe,CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, and like materials); a materialcomprising a first element selected from group 13 and a second elementselected from group 15 (e.g., GaN, GaP, GaAs, GaSb, InN, InP, InAs,InSb, and like materials); a material comprising a group 14 element (Ge,Si, and like materials); a material such as PbS, PbSe, PbTe, AlS, AlP,and AlSb; or an alloy or a mixture thereof. Further details regardingnanocrystalline structures for use in the present invention can befound, for example, WO 04/023527.

In a preferred embodiment, the devices of the present invention employnanocrystals comprising CdSe, CdTe and/or InP as the nanocrystalmaterials.

METHODS OF SYNTHESIZING CONDUCTIVE COMPOSITIONS

The present invention also provides methods of synthesizing an organicspecies that facilitates charge transfer, e.g., for use in ananostructure-containing photovoltaic device. The methods provide amodular approach to the synthesis procedure, such that various headgroups, tail groups, and side chains can be independently coupled to theselected body structure.

The methods of the present invention include the steps of a) providing aconjugated organic precursor, wherein the conjugated organic precursorcomprises at least three positions available for attachment ofsubstituent modules; b) providing a first substituent module (e.g., ahead group or other nanostructure binding moiety), wherein the firstsubstituent module comprises a nanostructure binding moiety, such as aphosphonic acid derivative, a carboxylic acid derivative, an aminederivative, a phosphine derivative, a thiol derivative, a thiophenederivative, or a combination thereof; and c) providing a secondsubstituent module (e.g., a tail group), wherein the second substituentmodule comprises an alkyne derivative comprising between three and 22carbons. Optionally, the method further includes providing a thirdsubstituent module (e.g., the sidechains), wherein the optional thirdsubstituent module comprises an alkyl derivative comprising between oneand 22 carbons. The substituent modules are then coupled to theconjugated organic precursor (e.g., the body structure): the firstsubstituent module at a first position, coupling the second substituentmodule at a second position, and the optional third substituent moduleat a third position, thereby synthesizing the organic composition. (Thefirst, second and third positions delineate available attachment siteson the conjugated organic moiety, and are not representative eitherorder of attachment during synthesis or IUPAC numbering conventions withrespect to the conjugated organic species). Typically, the optionalthird substituents are coupled to the body structure prior to attachmentof the first (head) and second (tail) substituents. Preferably, couplingof the modules to the body structure does not destroy the electronicconjugation of the body structure; furthermore, at least one substituentof the first, second or third substituent modules is capable of bindingto a nanostructure surface (or is already bound to a nanostructuresurface).

Synthesis of Core Body Structures with Attached Sidechain Moieties

The body structure provides the core of the conjugated organic speciesof the present invention. Typically, the body structure is a conjugatedorganic species that either can be functionalized (e.g., byhalogenation) or can be reacted with other functionalized moieties (headgroup, tail group, sidechains) to prepare the conductive compositions ofthe present invention.

Preferably, the conjugated organic precursor is selected from any of anumber of conjugated alkyl moieties or conjugated aryl moieties known toone of skill in the art. Exemplary conjugated organic precursors, suchas phenylene, thiophene, ethene, ethyne, aniline, fluorene, and pyridinederivatives, alkenyl moieties, or perylene, phenanthralene, anthracene,alkenyl or other polynuclear aromatic moieties (or polymeric derivativesthereof), have been discussed in previous sections. Optionally, couplingof one or more of the substituent modules to the body structure extendsthe conjugation of the body structure. Exemplary body structures areprovided in Table 2. TABLE 2 Exemplary conjugated organic moieties foruse as Body Structures S1

S2

S3

S4

S5

S6

One advantage to the convergent component synthesis (“modular”) approachto the design and manufacture of the conductive compositions of thepresent invention is the ability to adjust or “tune” the reactivity ofeach component for the synthetic scheme. For example, the rate ofaryl-aryl coupling can be increased or decreased by selecting anappropriate electron donating group or an electron withdrawing group oneach respective component. Electron withdrawing groups tend toaccelerate the oxidative addition step in palladium-catalyzed couplingreactions (see, e.g., Kuehl et. al. (1997) Organometallics 16: 1897).Thus, by including an electron withdrawing substituent on one of thecomponents, the rate of coupling increases. While not limiting thepresent invention to a specific mechanism, the enhancement in couplingmay be accomplished by the electron withdrawing group weakening the arylhalide or aryl-stannane bond, thus affording a more facile insertion ofthe palladium catalyst between these moieties. For example, attachingthe alkynyl tail group moiety to a thiophene precursor, followed bytrimethylstannane attachment, and subsequently coupling this componentto the body results in a faster coupling rate and higher overall yieldsthan stepwise assembly. A slower coupling rate is observed if thealkynyl moiety was added after the thiophene and body component werecoupled in a divergent stepwise fashion.

The conductive compositions of the present invention often include oneor two sidechains, or “arms,” (i.e., third and fourth substituentmodules) coupled to the body structure. In a preferred embodiment of themethods, the optional third and fourth substituent modules are coupledto the conjugated organic precursor prior to coupling the first (head)and/or second (tail) substituent modules. For example, the conjugatedorganic precursor can be alkylated at the third position having ahydroxyl or amine moiety, to form an O-linked or N-linkedsidechain-substituted intermediate composition.

For example, sidechain moieties functionalized with a halide (e.g., I orBr) can be used to alkylate the selected conjugated organic species andprovide a sidechain-substituted body structure using procedures known inthe art. As an example, for the hydroxyl-containing conjugated organicprecursors described herein, providing the third substituent modulecomprises providing about 1.1 molar equivalents of a halogenatedderivative of the selected sidechain substituent; and coupling the thirdsubstituent module with the conjugated organic precursor comprises thesteps of a) combining the halogenated sidechain derivative with theconjugated organic precursor in the presence of, e.g., potassiumcarbonate (K₂CO₃) and dimethyl formamide (DMF), to form a reactionmixture; and b) heating the reaction mixture to about 70° C., therebycoupling the third substituent to the conjugated organic moiety. Asimilar reaction can be designed for coupling functionalized sidechainmoieties to amine-containing body structure precursors. Alternatively,the sidechain-coupled body structure for use as a substrate ingenerating the compositions of the present invention can be purchasedfrom various suppliers (e.g., SIGMA-Aldrich) when available.

In the case of body structures having two (or more) identical sidechainmoieties, the coupling reactions for the third and fourth substituentsare typically performed simultaneously (e.g., in a single reactionmixture).

One preferred body structure used in the methods and compositions of thepresent invention is hydroquinone(1,4-dihydroxybenzene). Table 3provides exemplary substrates for use in the synthesis proceduresdescribed herein, based upon a hydroquinone body structure having twosidechain substitutions coupled at the hydroxyl positions of the corehydroquinone structure. TABLE 3 Exemplary Body Structures with AttachedSidechains A1

A2

A3

B1

B2

B3

C1

C2

C3

D1

D2

D3

E1

E2

E3

A4

As indicated in the tabular data above, the two sidechain elements atpositions 1 and 4 of the hydroquinone body structure can, but need not,be the same chemical entity.

Synthesis of Head Group Moieties

The first substituent module comprises the functionalizednanostructure-binding head group. For example, for embodiments in whichthe first substituent module comprises diethylphosphite, coupling thefirst substituent module to the body structure can be performed via apalladium-catalyzed phosphite-aryl coupling reaction.

In alternate embodiment, a larger head module (precursor) is preparedhaving a nanostructure binding moiety (e.g., a phosphite) and aconjugated species (e.g., a benzene ring or a thiophene) for linking thenanostructure binding moiety to the body structure. Synthesis of thehead module can be achieved, for example, by providing an arylhalidecore structure and performing two lithium-halogen exchange reactions.The arylhalide core structure is lithiated at a first halide positionand reacted with chlorotrimethylsilane (TMSCl) to yield a TMS-arylintermediate core structure; the TMS-intermediate core structure is thenlithiated at a second halide position and reacted withtrimethyltinchloride (Me₃SnCl) to yield a stannylated secondintermediate. Optionally, the lithiating reactions can be performed inthe reverse order. The product of these reactions is then combined with,e.g., a halogenated thiophene as the conjugated species, to form thefirst substituent module, which in this embodiment comprises aTMS-aryl-thiophene derivative. The nanostructure-binding moiety (e.g., aphosphite group) can then be coupled to the aryl portion of the boundhead group module, via a palladium-catalyzed mechanism (either before orafter attachment of the head module to the body structure).

Exemplary nanostructure binding moieties that can be used in the presentinvention include, but are not limited to, those depicted in Table 4.TABLE 4 Exemplary Synthetic Substrates having nanostructure BindingMoieties for use as Head Groups H1 —PO₃H₂ H2 —PO₃(CH₂CH₃)₂ H3

H4

H5

Synthesis of Tail Moieties

The conductive composition also includes a tail group, typicallypositioned distal to the nanostructure-binding head group. Optionally,the tail group can also include one or more nanostructure bindingmoieties; in these embodiment, the conductive compositions can be usedas a linker between adjacent nanostructures or nanostructures.Optionally, for embodiments having self-organizing propertiesincorporated therein, the conductive compositions of the presentinvention can also be employed as alignment ligands, e.g., for orientingand/or arranging the associated nanostructures (see, for example, U.S.Ser. No. [Attorney Docket No. 40-003300US] and PCT application [AttorneyDocket No. 40-003300PC] co-filed herewith).

Coupling of the second substituent module(e.g., the alkyne-containingtail moiety) can be accomplished by performing an aryl coupling reactionusing palladium catalysts. Exemplary reaction protocols include, but arenot limited to, Sonogashira couplings (Sonogashira et al. 1975Tetrahedron Lett. 50: 4467-4470), Suzuki couplings (Miyaura 1979Tetrahedron Lett. 3437), Hartwig-Buchwald couplings (for N-linkedsubstituents), Heck reactions (Patel et al. 1977 J. Org. Chem. 42:3903),and the like. Alternatively, copper-mediated reactions such as theUllmann coupling and Stephens-Castro coupling can be used to couple thesecond substituent module to the body structure. Optionally, thecatalyst (for this or for other reactions described herein) can beprovided on a solid support or coupled to a soluble polymer, to improverecovery of the material (see, for example, Bergbreiter “Solublepolymer-bound catalysts” Bergbreiter and Martin (Eds.), (1989)Functional Polymers (Plenum Press, New York, pp. 143-158); Tafesh andBeller (1995) “First Selective Reduction of Aromatic Nitro CompoundsUsing Water Soluble Catalysts” Tetrahedron Lett. 36:9305.

Exemplary chemical constituents for use as tail group moieties in thepresent invention include, but are not limited to, the structures shownin Table 5. TABLE 5 Exemplary Alkyne precursors for use as Tail GroupsT1

T2

T3

Modular Synthesis of Conductive Compositions

By preparing the body structure (with or without the optionalaccompanying sidechains), head group and tail group moieties separately,various different conductive compositions can easily and rapidly beprepared. This modular approach to the chemical synthesis of theconductive compositions of the present invention lends itself to anumber of combinations of various head moieties, tail groups, andoptional side chain elements, some of which are provided in FIG. 1 andFIG. 2.

Optionally, the synthetic methods further include the step of couplingthe head group to an external surface of a structure, such asnanocrystal (or other nanostructure), thereby providing ananocrystal-bound composition. Alternatively, the head group can becoupled to a non-nanoscale surface and the conductive compositionemployed in conjunction with a non-nanoscale semiconductor composition.Semiconductor and nanoscale semiconductor compositions are known in theart. Nanostructures having external surfaces that can be employed in thecoupling step can be prepared from any of the exemplary semiconductingmaterials described previously. In a preferred embodiment, thenanocrystals are group II/VI or group III/V structures, for whichcoupling the head group to the external surface of a nanocrystalcomprises, e.g., association of free electrons available in the headgroup with proximal metal moieties of the nanocrystal. The head groupmodule employed can be chosen based upon the composition of thestructure or nanoscale structure to be contacted, such that a conductivecomposition can be prepared, e.g., for any nanostructure/nanocrystalcomposition, without undue experimentation.

Furthermore, the methods of the present invention can also optionallyinclude the step of polymerizing the organic composition after couplingthe composition to the nanostructure surface, thereby forming apolymerized organic composition.

Nanostructure-containing device of the present invention areparticularly suited for use in a photovoltaic device. See, for example,Huynh et al. (2002) Science 295:2425-2427; Huynh et al. (1999) Adv.Mater. 11:923-927; Greenham et al. (1996) Phys. Rev. B-Condens Matter54:17628-17637; and Greenham et al. (1997) Synthetic Metals 84:545-546;as well as the exemplary nanocrystal-containing photovoltaic devicesdescribed in WO 2004/022637 and 04/023527. The conductive compositionsof the present invention can also be employed in thepolymer/nanocomposite photovoltaic devices described in U.S. Pat. No.6,239,355; U.S. Pat. No. 6,512,172, as well as dye-sensitized crystalphotovoltaic devices, e.g., as described in U.S. Pat. No. 5,728,487; andU.S. Pat. No. 6,245,988.

Synthesis of water soluble semiconductor nanocrystals capable of lightemission are described, for example, in U.S. Pat. No. 6,251,303 toBawendi et al. entitled “Water-soluble fluorescent nanocrystals” (Jun.6, 2001) and U.S. Pat. No. 6,319,426 to Bawendi et al. titled“Water-soluble fluorescent semiconductor” (Nov. 20, 2001).

METHOD OF MODIFYING INTERACTION BETWEEN NANOSTRUCTURE AND MATRIX

As an additional aspect, the present invention also provides methods ofmodifying an interaction between a nanostructure and an external matrix.The methods include the steps of a) treating a nanostructure with theconductive composition of the present invention; and b) forming ananostructure-containing matrix comprising the treated nanostructure anda matrix composition. Optionally, treating the nanostructure can alsoinclude polymerizing the conductive composition to form a polymerizedconductive composition. In some embodiments of the methods, thepolymeric conductive composition described herein are employed asmatrices in the methods.

USES OF THE METHODS, DEVICES AND COMPOSITIONS OF THE PRESENT INVENTION

Modifications can be made to the methods and materials as describedabove without departing from the spirit or scope of the invention asclaimed, and the invention can be put to a number of different uses,including:

The use of any method herein, to prepare a conductive composition foruse in modifying an interaction involving a nanostructure, e.g., aninteraction between a nanocrystal and a matrix.

The use of any method herein, to associate a conductive composition ofthe present invention with one or more nanostructures.

The use of a method or a conductive composition of the present inventionin the manufacture of a nanostructure-containing device.

A kit or system using of any one of the conductive compositions,nanostructure:conductive composition; nanostructure:matrix compositions,or methods hereinbefore described. Kits will optionally additionallycomprise instructions for performing the methods, packaging materials,one or more containers which contain the conductive compositions ormaterials used to prepare the compositions, and/or the like.

In an additional aspect, the present invention provides kits embodyingthe methods and devices herein. Kits of the invention optionallycomprise one or more of the following: (1) various components (bodystructures, head groups, tail groups, sidechains) for the modularsynthesis of the conductive compositions of the present invention; (2)one or more preparations of nanocrystals or other nanostructures; (3)components and/or instructions for the preparation of nanocrystal:matrixcompositions; (4) instructions for practicing the methods describedherein; and/or (5) packaging materials.

In a further aspect, the present invention provides for the use of anycomponent or kit herein, for the practice of any method herein, and/orfor the use of any apparatus or kit to practice any method herein.

EXAMPLES

The following examples are offered to illustrate, but not to limit theclaimed invention. It is understood that the examples and embodimentsdescribed herein are for illustrative purposes only and that variousmodifications or changes in light thereof will be suggested to personsskilled in the art and are to be included within the spirit and purviewof this application and scope of the appended claims.

Methods for the synthesis of the conductive compositions of the presentinvention are provided herein and in the accompanying figures.Additional information regarding synthesis techniques can be found in,for example, Fessendon and Fessendon, (1982) Organic Chemistry, 2ndEdition, Willard Grant Press, Boston Mass; Carey & Sundberg, (1990)Advanced Organic Chemistry, 3rd Edition, Parts A and B, Plenum Press,New York; and March (1985) Advanced Organic Chemistry, 3rd Edition, JohnWiley and Sons, New York. Optionally, the standard chemical reactionsdescribed therein are modified to enhance reaction efficiency, yield,and/or convenience.

Example 1 SYNTHESIS OF MODEL CONDUCTIVE COMPOSITION4-DECYNYL-BENZENE-1-PHOSPHONIC ACID

A synthesis protocol was designed to test the modular approach tosynthesis of the conductive compositions of the present invention (FIG.3). The model conductive composition 5b was prepared using1-iodo-4-bromobenzene as a precursor to the body structure, 1-decyne asthe tail group moiety, and diethylphosphite as the head group moiety. Toa 500 mL schlenk flask with egg-shaped stirbar under argon, palladiumdichloride (1.0 mmol, 0.177 g), copper(I) iodide (2.36 mmol, 0.450 g),and triphenylphosphine (2.0 mmol, 0.525 g) were added in a gloveboxunder argon. On a schlenk line, 1-iodo-4-bromo-benzene (50 mmol, 14.15g, compound 1) was added, the vessel was stoppered, and the flask wasplaced under vacuum and backfilled with argon (3×). The flask was fittedwith a septum under positive argon pressure and degassed diisopropylamine (100 mL) was added via cannula under positive argon pressure withstirring. Next, degassed 1-decyne (50 mmol, 6.91 g, compound 2) wasadded via syringe under argon. Finally, dry, degassed tetrahydrofuranwas added via cannula transfer under argon, the vessel sealed with aglass stopper and allowed to stir at ambient for 16 h followed byheating to 55° C. for one hour. After cooling to ambient temperature,the solvent was removed by roto-evaporation, the residue dissolved indiethyl ether (200 mL) and washed with ammonium chloride (sat. aqueous,3×100 mL). The organic layer was separated and dried over magnesiumsulfate, filtered and the solvent removed by roto-evaporation. Theresulting oil was dissolved in hexanes and plugged through silica gel.Removal of the solvent resulted in a yellow oil of4-decynyl-bromo-benzene 3 (14.34 g, 98% yield).

This material was used without further purification for the attachmentof phosphonate ester moiety. To a 100 mL schlenk tube with a Teflonvalve and stirbar containing the above compound 3 (23.87 mmol, 7.0 g),palladium(0)tetrakis[triphenylphosphine] (1.19 mmol, 1.38 g) was added.On a schlenk line, degassed triethyl amine (11 mL) and degassed toluenewere then sequentially added via syringe under argon. Next, degasseddiethyl phosphite 4 (26.26 mmol, 3.63 g) was added via syringe underargon. The reaction vessel was sealed, the mixture stirred and heated to100° C. for 2 h. The solvent was removed by roto-evaporation, and theresidue dissolved in ethyl acetate (200 mL) and washed with saturatedaqueous ammonium chloride (3×75 mL), dried over sodium sulfate, filteredand the solvent removed by roto-evaporation. Isolation by silica gelchromatography (1:1 Ethyl Acetate:Hexanes) afforded4-decynyl-benzene-1-diethylphosphonate 5a as a colorless oil (7.19 g,90% yield) ¹H NMR (CDCl₃) δ 7.70 (m, 2 H), 7.45 (m, 2 H), 4.10 (m, 4 H),2.42 (t, 2 H), 1.61 (m, 2 H), 1.45 (m, 2H), 1.32 (t, 8H), 1.27 (m, 6 H),0.89 (t, 3 H). MS signal derived from the phosphonated benzyl ringwithout the coupled tail group (a side product of the reaction) is shownin FIG. 9.

Hydrolysis of the ester to the phosphonic acid was accomplished by thefollowing. To a 250 mL schlenk flask containing compound 5a (10 mmol,3.5 g) and dry dichloromethane (65 mL), Trimethylsilylbromide (40 mmol,6.1 g) was added via syringe under argon with stirring. After stirringfor 4.5 h at ambient temperature, the solvent was removed in vacuo onthe schlenk line. Next acetone (32 mL) and water (0.775 mL) were addedand the mixture stirred at ambient temperature for 45 min. Removal ofthe acetone/water by roto-evaporation followed by addition ofdichloromethane and roto-evaporation of all solvent afforded thephosphonic acid derivative 5b (2.9 g, 100% yield). ¹H NMR (CDCl₃, FIG.18) δ 7.75 (m, 2 H), 7.45 (m, 2 H), 2.44 (t, 2 H), 1.63 (m, 2 H), 1.45(m, 2H), 1.32 (t, 8H), 0.93 (t, 3 H). {1H}³¹P NMR (CDCl₃, FIG. 19) δ24.0

Example 2 SYNTHESIS OF CONDUCTIVE COMPOSITION 16

One advantage to the methods of the present invention is the modularapproach to synthesis of the various conductive compositions ofinterest. Using this approach allows for the preparation and use ofcommon synthetic intermediates and core structures. An exemplarysynthesis scheme for the preparation of a conductive composition of thepresent invention is depicted in FIG. 4 and described in further detailherein. In this modular approach, the various components of thecomposition (body structure, head group, tail group) are synthesized asindividual structures, which are then coupled together to form theconductive composition.

Preparation of the Head Group Precursor

One common intermediate in the synthesis of some embodiments of thepresent invention is the activated head group precursor compound 9,which can be prepared based upon known synthetic protocols such as thoseprovided in FIG. 4.

Coupling of Sidearm Moieties to the Body Structure

In many of the embodiments of the present invention, the sidearmmoieties are coupled to the body element prior to incorporation of thehead and tail elements. One preferred sidearm component for use in theconductive composition is an O-linked hexyl moiety. As such, anotherintermediate useful for the synthesis of 2,5-dihexoxy-containingconductive compositions is 1,4 diiodo-2,5-dihexoxybenzene (compound 13;see also FIG. 14). This core structure consisting of an aromatic bodystructure (benzene) and the two O-linked sidearm chains can be preparedfrom hydroquinone (compound 10) by standard procedures such as providedin FIG. 4. While the following syntheses focus on hydroquinone-basedbody structures (e.g., various sidechains O-linked to a benzene core),other aryl and/or aromatic core structures are also contemplated and canbe used to generate conductive compositions of the present invention.Exemplary conductive compositions employing alternative core structuresare shown, for example, in FIG. 2.

Addition of Thiophene Elements to Body Structure

In a preferred embodiment, the body structure includes one or morethiophene moieties coupled to an aromatic ring core structure. This canbe achieved synthetically by either providing thiophene-containing corestructures or by providing thiophene-containing head or tail groupmoieties. An exemplary thiophene-containing body structure (includingthe coupled sidearms) is 1,4-dithiophene-2,5-dihexoxybenzene (compound15a). This compound, which is a precursor to the iodinated intermediatecompound 15b, is prepared as follows. To a 100 mL schlenk tube withstirbar and Teflon valve, palladium dichloride (1.0 mmol, 0.177 g),triphenylarsene (2.0 mmol, 0.610 g), and LiCl (20 mmol, 0.859 g) wereadded in a glove box. On a schlenk line, 1,4-diiodo-2,5-dihexoxybenzene13 (10 mmol, 5.30 g), was added and the vessel placed under vacuum andbackfilled with argon (3×). Next, degassed dimethylformamide (DMF) wascannula transferred under positive argon pressure. The vessel was sealedand heated to 100° C. for up to 6 days. The reaction mixture was cooledand diluted with ethyl acetate (200 mL) and washed with saturatedaqueous sodium bicarbonate (125 mL), deionized water (50 mL) and brine(150 mL). The organic layer was placed under vacuum and the solventremoved and trapped in a 250 mL schlenk flask. Purification by flashchromatography (Ethyl acetate:hexanes, 0, 1, 2, and 5% gradient) andsolvent removal by roto-evaporation afforded yellow crystals of1,4-dithiophene-2,5-dihexoxybenzene (2.2 g, 49% yield, compound 15a). ¹HNMR (CDCl₃, FIG. 16) δ 7.53 (d, 2 H), 7.34 (d, 2 H), 7.25 (s, 2H), 7.09(dd, 2 H), 4.09 (t, 4H), 1.91 (m, 4 H), 1.55 (m, 4H), 1.36 (m, 8H), 0.93(t, 6 H); ¹³C{¹H} (CDCl₃) δ 149.2, 139.3, 126.8, 125.8, 125.2, 123.0,112.9, 69.9, 31.9, 29.7, 26.2, 22.9, 14.4.

Intermediate 15a was then converted to compound 15b by iodination of oneof the thiophene elements as follows. To a 100 mL schlenk flask withTeflon valve and stirbar, 1,4-dithiophene-2,5-dihexoxybenzene 15a (2.49mmol, 1.10 g) was added and the flask closed with a stopper and placedunder vacuum and backfilled with argon (3×). Next, dry chloroform (30mL) was cannula transferred under positive argon pressure and themixture stirred. To the stirred solution under argon, N-iodosuccinimide(2.49 mmol, 0.560 g) was added in one portion, the reaction vesselsealed with a Teflon sleeved stopper and the reaction mixture stirred atambient temperature for 4.5 h then heated to 40° C. and stirred for anadditional 22 h. After cooling the crude reaction mixture was pluggedthrough silica gel (5% ethylacetate:95% hexane), then washed with 10%aqueous sodium thiosulfate (3×50 mL), brine (50 mL) and the organiclayer dried over sodium sulfate filtered and the solvent removed byroto-evaporation to afford the crude material compound 15b as a yellowoily solid (1.40 g, 99% yield). ¹H NMR (CDCl₃, FIG. 13) δ 7.53 (m, 1 H),7.43 (d, 1H), 7.35 (m, 1 H), 7.26-7.20 (m, 3H), 7.13 (d, 1H) 7.09 (dd, 1H), 7.02 (s, 1H), 4.09 (t, 4H), 2.45 (t, 2H), 1.93 (m, 4 H), 1.70-1.25(m, 24H), 0.94) (m, 9 H); MALDI-TOF MS (M+H) 569 m/z.

Coupling of the Tail and Head Groups

Addition of the tail group and head group moieties to the iodinatedintermediate 15b leads to conductive composition 16. The tail moiety iscoupled to the iodinated thiophene element of the body structure asshown in FIG. 4, in a manner similar to that previously described forcompound 5a. Coupling of the head group is the final step in thesynthesis of the desired conductive composition 16.

Example 3 SYNTHESIS OF COMPOSITIONS HAVING ASYMMETRIC SIDEARM ELEMENTS

The two sidearm moieties of the conductive composition need not beidentical or symmetrical in structure. In another embodiment of thecompositions of the present invention, two differing sidearm moietiesare employed in the modular synthesis of the conductive composition 21.As shown in FIG. 5, 4-methoxyphenol (compound 17) was alkylated at theunprotected hydroxyl group using 1.1 equivalents of 1-iodohexane(compound 11) in the presence of potassium carbonate and DMF at 70° C.,to form intermediate compound 18 (see FIG. 15), which was iodinated(compound 19, FIG. 17), derivatized with thiophene moieties, and coupledto a 1-decyne tail moiety (T1) and a thiophene-phosphonate head group(H3) in a manner similar to Example 2.

Example 4 SYNTHESIS OF TAIL GROUP MOIETY 1-STANNYL-5-DECYNYL-THIOPHENE

Another common intermediate employed in the synthesis of someembodiments of the present invention is the thiophene-containing tailgroup moiety, 1-stannyl-5-decynyl-thiophene (compound 22), in which athiophene moiety and tail group are joined prior to coupling to the bodystructure (in contrast to the synthetic schemes depicted in FIG. 4 andFIG. 5, in which the thiophene moiety is joined to the body structureprior to coupling of the tail group moiety). This thiophene-tail groupintermediate can be prepared as follows (FIG. 6). To a 100 mL schlenktube with resealable Teflon valve and egg-shaped stirbar, palladiumdichloride (0.413 mmol, 0.073 g), triphenylphosphine (0.826 mmol, 0.217g), and copper(I) iodide (0.413 mmol, 0.079 g) were added in the glovebox. On the schlenk line, degassed 2-bromothiophene 8 (20.66 mmol, 3.37g), diisopropyl amine (30 mL), 1-decyne 2 (20.66 mmol, 2.86 g) andtoluene (50 mL) were added sequentially via syringe under argon. Thereaction vessel was sealed with the valve, the reaction mixture heatedto 100° C. and stirred overnight. The reaction mixture was cooled toambient temperature, and the solvent removed by roto-evaporation. Theresidue was dissolved in diethyl ether (250 mL) washed with saturatedaqueous ammonium chloride (3×125 mL), dried over sodium sulfate,filtered, and the solvent was removed by roto-evaporation, affording ayellow oil. Purification by plugging through silica gel with hexanesafforded 2-decynyl thiophene (compound 22a) as a light yellow oil (4.32g, 95% yield). ¹H NMR (CDCl₃) δ 7.18 (d, 1 H), 7.12 (d, 2 H), 6.94 (dd,1H), 2.44 (t, 2 H), 1.70-1.30 (m, 12 H), 0.92 (t, 3 H); GC/MS (M⁺ 220m/z). This compound was used without further purification.

To a 1 L schlenk flask with egg-shaped stirbar in a glove box, the2-decynylthiophene 22a (57.44 mmol, 12.658 g) was added by pipette. On aschlenk line, tetrahydrofuran (300 mL) was cannula transferred to thereaction vessel through a septum. The reaction mixture was cooled to−78° C. and n-butyl lithium (35.9 mL, 1.6 M solution in hexanes,) wasadded dropwise via syringe and the reaction mixture stirred for 45 min.The reaction vessel was fitted with an addition funnel and trimethyltinchloride (57.4 mL, 1.0 M solution in tetrahydrofuran) was cannulatransferred to the funnel under positive argon pressure through aseptum. The trimethyltin chloride solution was added dropwise to thestirring lithium salt solution over a period of 15 min. at −78° C. Thereaction mixture was allowed to warm to ambient temperature withstirring overnight. The solvent was removed in vacuo on the schlenk lineand trapped in a 1 L schlenk flask. The resulting residue was dissolvedin diethyl ether (500 mL) washed with brine (3×200 mL), dried overmagnesium sulfate, filtered and the solvent removed by roto-evaporationto afford 1-stannyl-5-decynyl-thiophene 22b as a light brown oil (20.6g, 94% yield). ¹H NMR (CDCl₃) δ 7.20 (d, 1 H), 7.00 (d, 2 H), 2.43 (t, 2H), 1.60 (m, 2 H), 1.44(m, 2H), 1.30 (m, 8H), 0.899 (t, 3 H), 0.37 (s,9H); GC/MS (M⁺) 384 m/z, (M⁺-CH₃) 369 m/z.

Example 5 SYNTHESIS OF CONJUGATED COMPOSITION 25

Another example of a conjugated composition of the present invention iscompound 25 shown in Table 1 and FIG. 6. This composition was preparedusing the thiophene-derivatized tail group moiety 22b and body structure15b as follows.

To a 50 mL schlenk tube with a stirbar, palladium dichloride (0.12 mmol,0.021 g), triphenylarsene (0.24 mmol, 0.073 g), LiCl (2.4 mmol, 0.103 g)and 1-stannyl-5-decynyl-thiophene 22b, were added in a glove box. On aschlenk line, compound 15b was dissolved in degassed dimethylformamideand cannula transferred to the schlenk tube under positive argonpressure. The reaction mixture was placed under vacuum, backfilled withargon, the vessel sealed and heated to 100° C. for up to 4 days. Thereaction mixture was diluted with ethyl acetate (250 mL) and washed withde-ionized water (100 mL), the organic layer separated and solventremoved in vacuo. Purification by silica flash chromatography (4% ethylacetate:96% hexane) afforded a precursor to compound 23 (precursorstructure not shown) as a yellow oily solid (0.360 g, 23% yield). ¹H NMR(CDCl₃) δ 7.54 (m, 1 H), 7.35 (d, 1 H), 7.25-7.16 (m, 4H), 7.09 (dd, 1H), 4.09 (m, 4H), 1.93 (m, 4 H), 1.56 (m, 4H), 1.39 (m, 8H), 0.94 (m,9H); MALDI TOF MS (M+H) 661 m/z.

To a 50 mL schlenk flask with Teflon valve, stirbar and the precursor tocompound 23 (0.515 mmol 0.340 g) and chloroform (6.2 mL),N-iodosuccinimide (0.515 mmol, 0.116 g) was added in one portion underargon. The reaction vessel was sealed and the mixture heated to 40° C.for 22 h. The reaction mixture was diluted with ethyl acetate (100 mL)washed with 10% aqueous sodium thiosulfate (3×25 mL), brine (2×25 mL),dried over magnesium sulfate, filtered and plugged through silica gelwith ethyl acetate. Solvent removal by roto-evaporation afforded thecrude product 23 as a sticky yellow solid which was used without furtherpurification (0.402 g, 99%). ¹H NMR (CDCl₃) δ 7.72 (d, 1 H), 7.56 (m, 1H), 7.50 (d, 1H), 7.40-7.32 (m, 2H), 7.30-7.20 (m, 2H), 7.11 (dd, 1 H),5.18 (t, 2H), 4.13 (m, 4H), 2.15 (m, 2H), 1.95 (m, 4H), 1.58 (m, 8H),1.50-1.20 (m, 14H), 1.28 0.93 (m, 9 H).

In this particular embodiment of the invention, a thiophene-coupled headgroup moiety 24 was prepared for attachment to the body structure, viacoupling to the non-iodinated thiophene of compound 15b. Addition of theprecursor head group moiety 24 to the crude reaction product 23 to formconductive composition 25 was performed as provided in FIG. 6.

Example 6 SYNTHESIS OF CONJUGATED COMPOSITION 28

A further example of a conjugated composition of the present inventionis compound 28 as shown in Table 1 and FIG. 7. This composition wasprepared using the thiophene-containing body structure 15b and abenzyl-containing tail moiety in a similar manner as described in FIG.7. Alternatively, compound 28 could have been synthesized using theintermediate depicted in FIG. 10 (i.e., by using a body structure havingthe benzyl ring instead of a head group having the benzyl ring).

The conductive composition depicted in FIG. 11 could be synthesized in asimilar modular manner, using body structure 15b, a benzylated headgroup (such as shown in FIG. 9, and a thiophene-containing tail group(e.g., compound 22).

Example 7 AN ALTERNATE METHOD FOR MODULAR SYNTHESIS OF COMPOUND 25

An alternate modular approach to preparation of conductive composition25 is also contemplated, as depicted in FIG. 20. In this approach,dithiophene elements are attached as a unit to the body structure,rather than using thiophene-containing head and tail group components.In this synthetic approach, iodinated body structure 13 is prepared fromhydroquinone 10 as described above. The iodine moieties are thenreplaced with two dithiophene structures to form compound 30.Intermediate 30 is then joined to tail group 2 and a phosphonic acidhead group, as shown in FIG. 20, to form conductive composition 25.

Example 8 SYNTHESIS OF CONJUGATED COMPOSITION 31

Di-iodinated intermediate 13 can also be used in the synthesis of anadditional embodiment of the conductive compositions of the presentinvention, compound 31, as described in FIG. 21.

Example 9 SYNTHESIS OF POLYMERIZABLE CONDUCTIVE POLYMERS

Embodiments of the present invention are contemplated in which one ormore components of the conductive composition (e.g., body structure,head, tail) are present in multiple units. For example, some embodimentsinclude body structures prepared by coupling or polymerizing two or morebody structures. The coupling can be performed either prior to or afterattachment of the head and tail moieties to the respective bodystructure members. These embodiments are generically described asconductive compositions having the structure [H_(x)-B_(y)-T_(z)]_(n),wherein H comprises at least one functionalized head group capable ofbinding to a nanocrystal surface (or, for nanostructure-boundembodiments, at least one head group bound to a nanocrystal surface);wherein B comprises a body structure comprising one or more conjugatedorganic moieties, wherein a first conjugated organic moiety is coupledto a proximal functionalized head group or bound head group; wherein Tcomprises at least one tail group coupled to the body structure; andwherein x, y, z and n independently comprise integers equal to orgreater than 1.

FIG. 22 provides a synthetic scheme for preparation of a conductivecomposition (compound 36) incorporating two core body structurecomponents, a p-xylene unit (derived from compound 32) and anO-alkylated hydroxyquinone unit (compound 12). It should be noted,however, that although two body structure components are employed from asynthesis perspective, the final product (in this example, compound 36)can also be considered to have one large body component having twoaromatic rings coupled by a dithiophene moiety, and having a tail moietyattached to a first end of the overall body structure and a head moietyattached to a second end of the overall body structure. As with manyembodiments of the chemical compositions of the present invention, thedistinction between body structure, head group and tail group elementsis partially based upon the synthetic approach chosen (note the twomodular approaches to compound 25 as described above), and as suchshould not be considered limiting.

Compound 36 can be synthesized as provided in FIG. 23. In a similarmanner, compound 41 can also by synthesized as shown in FIG. 24. In thismodular approach, the first portion of the body structure (compound 38)is prepared and then coupled to the tail group 22 (to form intermediate39); a second body structure portion (compound 20) is stannylated andcoupled to a head group (to form intermediate 40), and then thesesynthetic intermediates are joined to form compound 41.

Compounds 36 and 41 are of particular interest, since these compositionsalso embody an additional optional feature of the present invention, oneof the polymerization aspects of the conductive composition. As shown inFIG. 23, the sidearm elements of the p-xylene derived portion of thebody structure can be reacted with a ketone functional group as shown inFIG. 23, for example, in the presence of a stereoselective base, such aslithium diisopropyl amide (LDA). The cross-reactivity between theketone-containing conductive compositions (preferably on differentnanostructures) leads to crosslinking of the adjacent conductivecompositions.

This embodiment is particularly of interest in nanostructure-matrixcompositions having both n-type and p-type nanocrystals incorporatedinto the matrix. Coupling of an n-type nanocrystal to an adjacent p-typenanocrystal will allow for an even more efficient transmission ofelectrons and holes within the matrix.

Example 10 SYNTHESIS OF CONDUCTIVE COMPOSITION 43

Di-iodinated intermediate 13 can also be used in the synthesis of anadditional embodiment of the conductive compositions of the presentinvention, compound 43 (see FIG. 25). For the synthesis of thiscompound, intermediate 30 is prepared as described above. The head groupand tail group moieties are then coupled to the body structure using theprotocols described in FIG. 25, to generate compound 43.

Example 11 SYNTHESIS OF CONDUCTIVE COMPOSITION 46

Di-iodinated intermediate 13 can also be used in the synthesis of anadditional embodiment of the conductive compositions of the presentinvention, compound 46 (see FIG. 26).

To a 50 mL schlenk flask with egg-shaped stirbar in a glove box,precursor 22b (0.997 mmol, 0.659 g) was added. The vessel was stoppered,placed under vacuo and backfilled with argon (3×). On a schlenk line,tetrahydrofuran (5 mL) was cannula transferred to the reaction vesselthrough a septum. The reaction mixture was cooled to −78° C. and n-butyllithium (0.623 mL, 1.6 M solution in hexanes,) was added dropwise viasyringe and the reaction mixture warmed to −50° C. and stirred for 1 h.The reaction mixture was recooled to −78° C. and trimethyltin chloride(0.997 mL, 1.0 M solution in tetrahydrofuran) was added dropwise viasyringe to the stirring lithium salt solution at −78° C. The reactionmixture was allowed to warm to ambient temperature with stirringovernight. The solvent was removed in vacuo on the schlenk line andtrapped in a 1 L schlenk flask. The resulting residue was extracted withhexanes (3×50 mL) and cannula filtered followed by in vacuo solventremoval to afford intermediate compound 44 as a yellow oil. ¹H NMR(CDCl₃) δ 7.67 (d, 1 H), 7.45 (d, 1 H), 7.28-7.22 (m, 2 H) 7.20 (d, 1H)7.15 (d, 1H), 7.03 (s, 2H), 4.12 (m, 4H), 2.46 (t, 2 H), 1.93 (m, 4H),1.62 (m, 2 H), 1.44 (m, 2H), 1.39 (m, 8H), 0.95 (m, 9 H), 0.37 (s, 9H).

To prepare functionalized head moiety 45, compound 13 (50.0 mmol, 14.15g) and palladium(0)tetrakis[triphenylphosphine] (2.50 mmol, 2.89 g) wereadded to a 200 mL schlenk tube with a Teflon valve and stirbar. On aschlenk line, degassed triethyl amine (20.9 mL) and degassed toluene (50mL) were then sequentially added via syringe under argon. Next, degasseddiethyl phosphite (50.0 mmol, 6.91 g) was added via syringe under argon.The reaction vessel was sealed, the mixture stirred at ambienttemperature for 12 h followed by heating to 50° C. for 1 h. The solventwas removed by roto-evaporation, and the residue dissolved in ethylacetate (500 mL) and washed with saturated aqueous ammonium chloride(3×200 mL), dried over magnesium sulfate, filtered and the solventremoved by roto-evaporation. Isolation by silica gel chromatography (1:1Ethyl Acetate:Hexanes) afforded scheme 2.3 compound 8 as a colorless oil(9.17 g, 62% yield) ¹H NMR (CDCl₃) δ 7.90-7.50 (m, 4 H), 4.30-4.10 (m, 4H) 1.50-1.30 (m, 6H); {1H}³¹P NMR (CDCl₃) δ 18.8 (s).

To a 50 mL schlenk tube with a stirbar, palladium dichloride (0.06 mmol,0.010 g), triphenylarsene (0.10 mmol, 0.031 g), LiCl (1.0 mmol, 0.043 g)and scheme 2.3 compound 8 (1.05 mmol, 0.370 g), were added in a glovebox. On a schlenk line, scheme 2.3 compound 7 was dissolved in degasseddimethylformamide (6 mL) and cannula transferred to the schlenk tubeunder positive argon pressure. The reaction mixture was placed undervacuum, backfilled with argon, the vessel sealed and heated to 100° C.for 12 h. The reaction mixture was diluted with ethyl acetate (250 mL)and washed with de-ionized water (100 mL), the organic layer separatedand solvent removed in vacuo. Purification by silica flashchromatography (ethyl acetate:hexane 1:1) afforded Scheme 2.3 compound 9as a yellow oily solid (0.124 g, 14% yield). ¹H NMR (CDCl₃) δ 7.85-7.80(m, 2 H) 7.76-7.72 (m, 2H) 7.65 (d, 1 H), 7.46 (d, 1 H), 7.42 (d, 2 H)7.25 (m, 2H) 7.15 (d, 1H), 7.04 (s, 1H), 7.03 (s, 1H) 4.15 (m, 4H), 2.46(t, 2 H), 1.97 (m, 4H), 1.62 (m, 2 H), 1.42 (m, 2H), 1.37 (m, 8H), 0.95(m, 9 H); {1H}³¹P NMR (CDCl₃) δ 19.6 (s).

Example 12 SYNTHESIS OF CONDUCTIVE COMPOSITION 50

Compound 50 is prepared using iodinated body structure 48, as shown inFIG. 27. To a 250 mL schlenk tube with stirbar and Teflon valve,palladium dichloride (2.05 mmol, 0.363 g), triphenylarsene (4.1 mmol,1.255 g), and LiCl (41 mmol, 1.759 g) were added in a glove box. On aschlenk line, 1,4-diiodo-2-(2-ethylhexoxy)-5-methoxybenzene (compound47b, 20.5 mmol, 10.0 g), was added and the vessel placed under vacuumand backfilled with argon (3×). Next, degassed dimethylformamide (DMF,100 mL) was cannula transferred under positive argon pressure. Thevessel was sealed and heated to 100° C. for 1 day. The reaction mixturewas cooled and diluted with ethyl acetate (500 mL) and washed withsaturated aqueous sodium thiosulfate (3×150 mL) and brine (3×150 mL).The organic layer was separated, dried over sodium sulfate, filtered andthe solvent removed by roto-evaporation. Purification by flashchromatography (Ethyl acetate:hexanes, 0, 1, 2, 5 and 10% gradient) andsolvent removal by roto-evaporation afforded of1,4-dithiophene-2-(2-ethylhexoxy)-5-methoxybenzene (7.55 g, 92% yield)as a colorless oil. ¹H NMR (CDCl₃) δ 7.56 (m, 2 H), 7.37 (d, 2 H), 7.29(s, 1H), 7.26 (s, 1H), 7.13 (m, 2 H), 4.01 (d, 2H), 3.97 (s, 3H), 1.87(m, 1 H), 1.61 (m, 4H), 1.38 (m, 8H), 1.00 (t, 3 H), 0.98 (t, 3H).

To a 500 mL schlenk flask with egg-shaped stirbar in a glove box, thereaction product (16.85 mmol, 6.75 g) was added. The vessel wasstoppered, placed under vacuo and backfilled with argon (3×). On aschlenk line, tetrahydrofuran (241 mL) was cannula transferred to thereaction vessel through a septum. Next N,N-Tetramethyl ethylenediamine(16.85 mmol, 1.96 g) was transferred to the reaction mixture viasyringe. The reaction mixture was cooled to −78° C. and n-butyl lithium(10.53 mL, 1.6 M solution in hexanes,) was added dropwise via syringeand the reaction mixture was stirred for 1 h. A THF solution (70 mL) of1,2-diiodoethane (21.91 mmol, 6.174 g) was cannula transferred to thestirring lithium salt solution at −78° C. The reaction mixture wasallowed to warm to ambient temperature with stirring overnight. Thesolvent was removed by roto-evaporation and the residue dissolved inethyl acetate (225 mL) and washed with 10% sodium thiosulfate (1×150 mL)and brine (200 mL). The organic layer was separated, dried overmagnesium sulfate, filtered and the solvent removed by roto-evaporation.Purification by flash chromatography (Ethyl acetate:hexanes, 0, 1, 2, 5and 10% gradient) and solvent removal by roto-evaporation afforded4-iodo-(1,4-dithiophene-2-(2-ethylhexoxy)-5-methoxybenzene (compound 48,6.21 g, 70% yield) as a yellow oil. ¹H NMR (CDCl3) δ 7.55 (m, 1 H), 7.38(d, 1 H), 7.29 (s, 1H), 7.25 (d, 1H), 7.21 (d, 1H), 7.20 (s, 1H), 7.13(dd, 1 H), 4.01 (d, 2H), 3.99 (s, 3H), 1.88 (m, 1 H), 1.61 (m, 4H), 1.36(m, 8H), 1.01 (t, 3 H), 0.98 (t, 3H).

The iodinated body structure 48 is then coupled to the tail moiety toform intermediate compound 49 (as described in FIG. 27). To a 100 mLschlenk tube with a stirbar, palladium dichloride (0.32 mmol, 0.057 g),triphenylarsene (0.64 mmol, 0.197 g), LiCl (6.43 mmol, 0.277 g) and1-stannyl-5-decynyl-thiophene 22b, were added in a glove box. On aschlenk line, compound 48 was dissolved in degassed dimethylformamideand cannula transferred to the schlenk tube under positive argonpressure. The reaction mixture was placed under vacuum, backfilled withargon, the vessel sealed and heated to 100° C. for up to 1 day. Thereaction mixture was diluted with ethyl acetate (250 mL) and washed withde-ionized water (100 mL), the organic layer separated and solventremoved in vacuo. Purification by silica flash chromatography (5-15%ethyl acetate:95-85% hexane) afforded the precursor compound as a yellowoil (2.83 g, 71% yield). ¹H NMR (CDCl₃) δ 7.57 (d, 1 H), 7.47 (m, 1 H),7.38 (m, 1H), 7.32-7.25 (m, 2 H), 7.17 (d, 1H), 7.13 (dd, 1H) 7.09-7.00(m, 2H), 4.00 (m, 2H), 3.99 (s, 3H), 2.47 (t, 2H) 1.87 (m, 1H), 1.63 (m,4H), 1.45 (m, 2H), 1.36 (m, 8H), 1.30-0.94 (m, 9H)); MALDI TOF MS (M+H)618 m/z.

To a 100 mL schlenk flask with egg-shaped stirbar in a glove box,precursor 49 (4.56 mmol, 2.82 g) was added. The vessel was stoppered,placed under vacuo and backfilled with argon (3×). In a drybox,tetrahydrofuran (23.3 mL) was pipetted to the reaction vessel and thesubstrate dissolved at ambient temperature. The reaction mixture wascooled to −78° C. and n-butyl lithium (2.85 mL, 1.6 M solution inhexanes,) was added dropwise via syringe and the reaction mixture warmedto −50° C. and stirred for 1 h. The reaction mixture was recooled to−78° C. and diethylphosphonate chloride (0.4.56 mmol, 0.658 mL) wasadded dropwise via syringe to the stirring lithium salt solution at −78°C. The reaction mixture was allowed to warm to ambient temperature withstirring overnight. The solvent was removed by roto-evaporation and theresulting residue was dissolved in ethyl acetate (150 mL), dried oversodium sulfate, filtered. Purification by silica flash chromatography(5-15% ethyl acetate:95-85% hexane) afforded the precursor compound asan orange oil.

Example 13 SYNTHESIS OF CONDUCTIVE COMPOSITION 25

FIG. 28 provides an alternate approach to the synthesis of conductivecomposition 25.

Example 14 PREPARATION OF NANOSTRUCTURES

Excess organic surfactants such as trioctyl phosphine (TOP), trioctylphosphine oxide (TOPO), hexadecyl phosphonic acid (HDPA), octadecylphosphonic acid (ODPA), and tri-n-butyl phosphine (TBP) are commonlypresent in nanostructure preparations as prepared by standard techniquescited herein. Optionally, any excess organic surfactant is removed fromthe nanostructure preparation prior to association with the conductivecompositions of the present invention. This can be achieved, forexample, by adding a solvent mixture prepared from a first solvent inwhich a nanostructure is soluble (e.g., toluene or chloroform) and asecond solvent in which the nanostructure is not soluble (e.g.,isopropanol or longer chain alcohol, or an acetate such as ethylacetate). While the ratio of first solvent to second solvent as preparedin the solvent mixture typically ranges between 1:1 and 10:1, onepreferred solvent mixture is 4 parts toluene to one part isopropanol.

An additional quantity of the second solvent is then added in a quantitysufficient to precipitate the nanostructures (but not the excesssurfactants) from the solvent mixture. The precipitated nanostructuresare then separated from the solvent mixture (e.g., by centrifuging),thereby removing excess organic surfactant from the nanostructures.Optionally, the precipitated nanostructures can be washed with thesolvent mixture one or more additional times, e.g., if analysisdetermines that the nanostructure preparation still contains anundesirable quantity of excess surfactant.

Additionally, any excess organic salts can be removed from thenanocrystal reaction mixture by performing a pyridine exchange on thenanocrystals in the nanocrystal reaction mixture, and precipitating theorganic salts while leaving the nanocrystals in solution. The pyridineexchange is performed, for example, by heating the nanocrystal reactionmixture to 150° C. for about 1 hour.

While the foregoing invention has been described in some detail forpurposes of clarity and understanding, it will be clear to one skilledin the art from a reading of this disclosure that various changes inform and detail can be made without departing from the true scope of theinvention. For example, all the techniques and apparatus described abovecan be used in various combinations. All publications, patents, patentapplications, and/or other documents cited in this application areincorporated by reference in their entirety for all purposes to the sameextent as if each individual publication, patent, patent application,and/or other document were individually indicated to be incorporated byreference for all purposes.

1. A polymeric conductive composition comprising the structure[Hx-By-Tz]_(n), wherein H comprises at least one functionalized headgroup capable of binding to a nanostructure surface or at least one headgroup bound to a nanostructure surface; wherein B comprises a bodystructure comprising one or more conjugated organic moieties, wherein afirst conjugated organic moiety is coupled to a proximal functionalizedhead group or bound head group; wherein T comprises at least one tailgroup coupled to the body structure; and wherein x, y, z and nindependently comprise integers equal to or greater than 1 and whereinx+y+z+n is equal to or greater than
 5. 2. The polymeric conductivecomposition of claim 1, wherein the head group comprises one or morephosphonic acid, carboxylic acid, amine, phosphine, or thiol moieties.3. The polymeric conductive composition of claim 1, wherein the bodystructure comprises a phenylene, thiophene, ethene, ethyne, aniline,fluorene, pyridine, perylene, phenanthralene, anthracene, alkenyl orpolynuclear aromatic moiety.
 4. The polymeric conductive composition ofclaim 1, wherein the body structure comprises poly(phenylene),poly(thiophene), poly(ethene), poly(ethyne), poly(aniline),poly(fluorene), poly(pyridine) moiety, or poly(polynuclear aromatic)moiety.
 5. The polymeric conductive composition of claim 1, wherein thetail group comprises 1-propyne, 1-butyne, 1-pentyne, 1-hexyne,1-heptyne, 1-octyne, 1-nonyne, 1-decyne, or an alkyne comprising between3 and 22 carbons.
 6. The polymeric conductive composition of claim 1,wherein the body structure further comprises one or more O-linked orN-linked substituents coupled to one or more member conjugated organicmoieties, wherein the substituents alter an electronic signature or asolubility of the polymeric conductive composition.
 7. The polymericconductive composition of claim 6, wherein the polymeric conductivecomposition is polymerized through polymerizable elements on the one ormore substituents.
 8. The polymeric conductive composition of claim 6,wherein the one or more substituents independently comprise an electrondonating group, an electron withdrawing group, a conducting chemicalstructure, or a nonconducting chemical structure.
 9. Ananostructure-containing matrix composition comprising: a nanostructurecomprising an exterior surface; and a matrix composition positionedproximal to the exterior surface of the nanostructure, wherein thematrix composition comprises a conductive polymer having the structure[Tx-By-Hz]_(n), wherein H comprises at least one functionalized headgroup capable of binding to a nanostructure surface; wherein B comprisesa body structure comprising one or more conjugated organic moieties,wherein a first conjugated organic moiety is coupled to the at least onefunctionalized head group; wherein T comprises at least one tail groupcoupled to the body structure; and wherein x, y, z and n independentlycomprise integers equal to or greater than
 1. 10. Thenanostructure-containing matrix composition of claim 9, wherein aportion of the nanocrystal exterior surface is conjugated with aconductive composition comprising: a body structure comprising aconjugated organic moiety; a head group coupled to the body structure ata first position on the conjugated organic moiety, wherein the headgroup comprises a functionalized head group capable of binding to ananostructure surface or a head group bound to a nanostructure surface;and a tail group coupled to the body structure at a second position onthe conjugated organic moiety; wherein one or more elements of theconductive composition are capable of removing or adding charges to ananostructure upon attachment to a surface of the nanostructure, therebymodifying charge transport across a nanostructure-containing matrix. 11.The nanostructure matrix composition of claim 10, wherein the matrixcomposition and the conductive composition are matched functionallyand/or electronically.
 12. The nanostructure matrix composition of claim10, wherein the matrix composition and the conductive composition arecovalently coupled.
 13. The nanostructure matrix composition of claim10, wherein the nanostructure is a nanocrystal.
 14. A method ofsynthesizing an organic composition that facilitates charge transfer foruse in a nanostructure-containing device, the method comprising: a)providing a conjugated organic precursor, wherein the conjugated organicprecursor comprises at least three positions available for attachment ofsubstituent modules; b) providing a first substituent module, whereinthe first substituent module comprises a phosphonic acid derivative, acarboxylic acid derivative, an amine derivative, a phosphine derivative,a thiol derivative, a thiophene derivative, or a combination thereof; c)providing a second substituent module, wherein the second substituentmodule comprises an alkyne derivative comprising between three and 22carbons; and d) optionally providing a third substituent module, whereinthe optional third substituent module comprises an alkyl derivativecomprising between one and 22 carbons; e) coupling the first substituentmodule at a first position, coupling the second substituent module at asecond position, and optionally coupling the third substituent module ata third position, thereby synthesizing the organic composition; whereincoupling of the modules to the body structure does not destroy anelectronic conjugation of the body structure, and, wherein at least onesubstituent of the first, second or third substituent modules is capableof binding to a nanostructure surface or is already bound to ananostructure surface.
 15. The method of claim 14, wherein theconjugated organic precursor comprises a conjugated alkyl moiety or aconjugated aryl moiety.
 16. The method of claim 15, wherein theconjugated organic precursor comprises a phenylene, thiophene, ethene,ethyne, aniline, fluorene, pyridine, perylene, phenanthralene,anthracene, alkenyl or polynuclear aromatic derivative.
 17. The methodof claim 15, wherein the conjugated organic precursor comprises apoly(phenylene), poly(thiophene), poly(ethene), poly(ethyne),poly(aniline), poly(fluorene), or poly(pyridine) derivative.
 18. Themethod of claim 14, wherein coupling of one or more of the substituentmodules to the body structure extends the conjugation of the bodystructure.
 19. The method of claim 14, wherein the optional thirdsubstituent module is coupled to the conjugated organic precursor priorto coupling the first and/or second substituent modules.
 20. The methodof claim 14, wherein providing the first substituent module comprisesproviding a thiophene derivative.
 21. The method of claim 20, whereinproviding the first substituent module comprises: a) providing anarylhalide core structure; b) lithiating the arylhalide core structureat a first halide position and reacting with chlorotrimethylsilane(TMSCl) to yield a TMS-aryl intermediate core structure; c) lithiatingof the TMS-intermediate core structure at a second halide position andreacting with trimethyltinchloride (Me3SnCl) to yield a stannylatedsecond intermediate; and, d) combining the second intermediate with ahalogenated thiophene to form a first substituent module comprising aTMS-aryl-thiophene derivative.
 22. The method of claim 20, wherein thefirst substituent module comprises an aryl-thiophene moiety and whereincoupling the first substituent module comprises: a) performing a Stillecoupling to form an iodinated intermediate; b) exchanging an iodinesubstituent of the iodinated intermediate for a TMS substituent; and, c)coupling a phosphite group to the aryl portion of the bound firstsubstituent module via a palladium-catalyzed mechanism.
 23. The methodof claim 20, wherein the first substituent module comprisesdiethylphosphite, and wherein coupling the first substituent modulecomprises performing a palladium-catalyzed phosphite-aryl coupling. 24.The method of claim 14, wherein coupling the second substituent modulecomprises performing a Sonogashira coupling.
 25. The method of claim 14,wherein the steps of providing the first substituent and/or providingthe second substituent comprise generating thiophene derivatives of thefirst and/or second substituents.
 26. The method of claim 14, whereincoupling the optional third substituent module comprises alkylating theconjugated organic precursor at third position comprising a hydroxyl oramine moiety, to form a sidechain-substituted intermediate composition.27. The method of claim 14, wherein providing the third substituentmodule comprises providing about 1.1 molar equivalents of a halogenatedderivative of a sidechain substituent; and wherein coupling the thirdsubstituent module with the conjugated organic precursor comprises: a)combining the halogenated derivative with the conjugated organicprecursor in the presence of potassium carbonate (K₂CO₃) and dimethylformamide (DMF) to form a reaction mixture; and, b) heating the reactionmixture to about 70° C., thereby coupling the third substituent to theconjugated organic moiety.
 28. The method of claim 14, wherein couplingthe third substituent further comprises coupling a fourth substituent tothe body structure at a fourth position.
 29. The method of claim 28,wherein the third substituent and the fourth substituent comprisesdifferent chemical species.
 30. The method of claim 28, wherein thethird substituent and the fourth substituent comprises identicalchemical species, and wherein the steps of coupling the firstsubstituent and coupling the fourth substituent are performed in asingle reaction mixture.
 31. The method of claim 14, further comprising:f) coupling the head group to an external surface of a nanocrystal,thereby providing a nanocrystal-bound composition.
 32. The method ofclaim 31, wherein the nanostructure comprises CdTe or InP.
 33. Themethod of claim 31, wherein coupling the head group to the externalsurface of the nanostructure comprises interacting one or more freeelectrons in the head group with proximal metal moieties of thenanostructure.
 34. The method of claim 31, further comprising: g)polymerizing the organic composition after coupling the composition tothe nanocrystal surface, thereby forming a polymerized organiccomposition.
 35. The method of claim 14, wherein thenanostructure-containing device comprises a photovoltaic device.
 36. Amethod of modifying an interaction between a nanostructure and anexternal matrix, the method comprising: treating a nanostructure with aconductive composition comprising: a body structure comprising aconjugated organic moiety; a head group coupled to the body structure ata first position on the conjugated organic moiety, wherein the headgroup comprises a functionalized head group capable of binding to ananostructure surface or a head group bound to a nanostructure surface;and a tail group coupled to the body structure at a second position onthe conjugated organic moiety; wherein one or more elements of theconductive composition are capable of removing or adding charges to ananostructure upon attachment to a surface of the nanostructure, therebymodifying charge transport across a nanostructure-containing matrix;and, forming a nanostructure-containing matrix comprising the treatednanostructure and a matrix composition.
 37. The method of claim 36,wherein treating the nanostructure further comprises polymerizing theconductive composition to form a polymerized conductive composition. 38.The method of claim 36, wherein the nanostructure is a nanocrystal. 39.A device comprising: a) a first electrode surface; b) the nanostructurematrix composition of claim 9 electrically coupled to the firstelectrode surface; and, c) a second electrode surface electricallycoupled to the nanostructure-containing matrix composition.
 40. Thedevice of claim 39, wherein the nanostructure matrix compositioncomprises one or more nanocrystals.
 41. A device comprising: d) a firstelectrode surface; e) the nanostructure-containing matrix composition ofclaim 14 electrically coupled to the first electrode surface; and, f) asecond electrode surface electrically coupled to thenanostructure-containing matrix composition.
 42. The device of claim 41,wherein the nanostructure-containing matrix composition comprises one ormore nanocrystals.